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Doping dependence of the upper critical field in La_{2-x}Sr_xCuO_4 from specific heatMar 05 2008The low-temperature specific heat of La_{2-x}Sr_xCuO_4 (LSCO) single crystals in magnetic field H up to 12 T has been examined over a wide range of doping (0.063=< p =<0.238). From this we have mapped the upper critical field H_{c2} of LSCO across the ... More

Vortex-unbinding and finite-size effects in Tl2Ba2CaCu2O8 thin filmsFeb 28 2003Oct 01 2003Current-voltage ($I$-$V$) characteristics of Tl$_2$Ba$_2$CaCu$_2$O$_8$ thin films in zero magnetic field are measured and analyzed with the conventional Kosterlitz-Thouless-Berezinskii (KTB) approach, dynamic scaling approach and finite-size scaling approach, ... More

Two energy scales and close relationship between the pseudogap and superconductivity in underdoped cuprate superconductorsAug 29 2007Sep 29 2007By measuring the low temperature specific heat, the low energy quasi-particle excitation has been derived and analyzed in systematically doped La$_{2-x}$Sr$_{x}$CuO$_{4}$ single crystals. The Volovik's relation predicted for a d-wave superconductor has ... More

Multi-band effect in the noncentrosymmetric superconductors Mg_{12-δ}Ir_{19}B_{16} revealed by Hall effect and magnetoresistance measurementsJun 09 2010We report the longitudinal resistivity and Hall effect measurements on the noncentrosymmetric superconducting Mg$_{12-\delta}$Ir$_{19}$B$_{16}$ samples with different critical transition temperatures. A strong temperature dependence of the Hall coefficient ... More

Comparative study of vortex dynamics in CaKFe4As4 and Ba0.6K0.4Fe2As2 single crystalsDec 17 2018We investigate the vortex dynamics in two typical hole doped iron based superconductors CaKFe$_4$As$_4$ (CaK1144) and Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ (BaK122) with similar superconducting transition temperatures. It is found that the magnetization hysteresis ... More

Contrasting Pair-Breaking Effects by Doping Mn and Zn in Ba0.5K0.5Fe2As2Jan 07 2010May 05 2010Resistivity, Hall effect, magnetoresistance and DC magnetization were measured in Mn and Zn doped Ba$_{0.5}$K$_{0.5}$Fe$_{2}$As$_{2}$ samples. It is found that the Mn-doping can depress the superconducting transition temperature drastically with a rate ... More

Possible Kondo effect in the iron arsenidesJan 19 2009Jan 25 2009The normal state of the iron arsenides shows the poor metallic behavior mixed with strong magnetic fluctuations. In particular, some FeAs-1111 and FeAs-122 compounds show the linear-T dependence of susceptibility above the spin-density wave (SDW) transition ... More

Magnetization Relaxation and Collective Vortex Pinning in the Fe-Based Superconductor SmFeAsO_0.9F_0.1Jun 05 2008Sep 20 2008By measuring the dynamic and traditional magnetization relaxations we investigate the vortex dynamics of the newly discovered superconductor SmFeAsO_0.9F_0.1 with Tc = 55K. It is found that the relaxation rate is rather large reflecting a small characteristic ... More

Pressure induced superconductivity in Bi single crystalsOct 19 2016Measurements on resistivity and magnetic susceptibility have been carried out for Bi single crystals under pressures up to 10.5GPa. The temperature dependent resistivity shows a semimetallic behavior at ambient and low pressures (below about 1.6GPa). ... More

Low temperature specific heat in BaFe1.9Ni0.1As2 single crystalsMar 25 2010Low-temperature specific heat was measured on the BaFe1.9Ni0.1As2 single crystals with critical transi-tion temperature Tc = 20.1 K. A clear specific heat jump with the value \DeltaC/T|Tc \approx 23 mJ/mol K^2 has been observed. In addition, a roughly ... More

Growth and Characterization of Bi$_{2+x}$Sr$_{2-x}$CuO$_{6+δ}$ Single CrystalsNov 14 2006Sep 16 2008High-quality Bi$_{2+x}$Sr$_{2-x}$CuO$_{6+\delta}$(0$<$x$\leq$0.5) single crystals have been grown successfully using the travelling-solvent floating-zone(TSFZ) technique. The samples with $x >$ 0.05 are in the underdoped level. The structure of these ... More

Synergy and competition between superconductivity and antiferromagnetism in FeSe under pressureNov 28 2018Temperature dependence of resistivity under high pressures with magnetic fields parallel and perpendicular to the FeSe planes are measured in FeSe single crystals. It is found that the structural transition (nematic) temperature is suppressed by pressure ... More

BaFe2Se2O as an Iron-Based Mott Insulator with Antiferromagnetic OrderJun 27 2012Jul 11 2012A new compound with a quasi-two-dimensional array of FeSe3O tetrahedra and an orthorombic structure, namely BaFe2Se2O, has been successfully fabricated. Experimental results show that this compound is an insulator and has an antiferromagnetic (AF) transition ... More

Reversibly tuning the insulating and superconducting state in KxFe2-ySe2 crystals by post-annealingMar 07 2011Since the discovery of superconductivity at 26 K in oxy-pnictide LaFeAsO1-xFx, enormous interests have been stimulated in the field of condensed matter physics and material sciences. Among the many kind of structures in the iron pnictide superconductors, ... More

Growth and post-annealing studies of La-Bi2201 single crystalsNov 05 2008Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+\delta}$ (0$\leq x \leq$1.00) single crystals with high-quality have been grown successfully using the travelling-solvent floating-zone technique. The patterns of X-ray diffraction suggest high crystalline quality of the ... More

Magnetization of potassium doped p-terphenyl and p-quaterphenyl by high pressure synthesisJun 19 2017By using high pressure synthesis method, we have fabricated the potassium doped para-terphenyl. The temperature dependence of magnetization measured in both zero-field-cooled and field-cooled processes shows step like transitions at about 125 K. This ... More

Pressure Induced Superconductivity in the New Compound ScZrCo1-$δ$Oct 11 2017It is widely perceived that the correlation effect may play an important role in several unconventional superconducting families, such as cuprate, iron-based and heavy-fermion superconductors. The application of high pressure can tune the ground state ... More

Nodal Superconducting Gap in $β$-FeSDec 13 2015Low temperature specific heat has been measured in superconductor $\beta$-FeS with T$_c$ = 4.55 K. It is found that the low temperature electronic specific heat C$_e$/T can be fitted to a linear relation in the low temperature region, but fails to be ... More

Superconductivity in LiOHFeS single crystals with a shrunk c-axis lattice constantDec 12 2016By using a hydrothermal ion-exchange method, we have successfully grown superconducting crystals of LiOHFeS with ${T_c}$ of about 2.8 K. Being different from the sister sample (Li${_{1-x}}$Fe${_x}$)OHFeSe, the energy dispersion spectrum analysis on LiOHFeS ... More

Vortex lattice and vortex bound states in CsFe$_2$As$_2$ investigated by scanning tunneling microscopy/spectroscopyJan 08 2018Jul 11 2018We investigate the vortex lattice and vortex bound states in CsFe$_2$As$_2$ single crystals by scanning tunneling microscopy/spectroscopy (STM/STS) under various magnetic fields. A possible structural transition or crossover of vortex lattice is observed ... More

Preliminary study on parameter estimation accuracy of supermassive black hole binary inspirals for TianQinJan 08 2019We use Fisher information matrix method to calculate the parameter estimation accuracy of inspiralling supermassive black holes binaries for TianQin, a space-borne laser interferometric detector aimed at detecting gravitational waves in millihertz frequency ... More

Unprecedented High Irreversibility Line in Nontoxic Cuprate Superconductor (Cu,C)Ba2Ca3Cu4O11+deltaMay 15 2018One of the key factors limiting the high power applications for a type-II superconductor is the irreversibility line Hirr(T) which reflects the very boundary of resistive dissipation in the phase diagram of magnetic field versus temperature. In cuprate ... More

Zero-Energy Modes on Superconducting Bismuth Islands Deposited on Fe(Te,Se)May 14 2019Topological superconductivity is one of the frontier research directions in condensed matter physics. One of the unique elementary excitations in topological superconducting state is the Majorana fermion (mode) which is its own antiparticle and obeys ... More

Upper critical field and quantum oscillations in tetragonal superconducting FeSAug 03 2016Sep 26 2016The magnetoresistance and magnetic torque of FeS are measured in magnetic fields $B$ of up to 18 T down to a temperature of 0.03 K. The superconducting transition temperature is found to be $T_c$ = 4.1 K, and the anisotropy ratio of the upper critical ... More

Multi-band superconductivity and large anisotropy in FeS crystalsNov 27 2015Feb 19 2016By using a hydrothermal method, we have successfully grown crystals of the newly discovered superconductor FeS, which has an isostructure of the iron based superconductor FeSe. The superconductivity appears at about 4.5K, as revealed by both resistive ... More

Strong coupling superconductivity revealed by scanning tunneling microscope in tetragonal FeSMay 17 2016Jul 27 2016We investigate the electronic properties of the tetragonal FeS superconductor by using scanning tunneling microscope/spectroscopy. It is found that the typical tunneling spectrum on the top layer of sulfur can be nicely fitted with an anisotropic s-wave ... More

Possible superconducting fluctuation and pseudogap state above $T_c$ in CsFe$_2$As$_2$Apr 25 2016Resistive, magnetization, torque, specific heat and scanning tunneling microscopy measurements are carried out on the hole heavily doped CsFe$_2$As$_2$ single crystals. A characteristic temperature $T^*\sim13$ K, which is several times higher than the ... More

Structures and Physical Properties of CsV$_2$Se$_{2-x}$O and V$_2$Se$_2$OMar 02 2018By using solid-state reactions, we successfully synthesize new oxyselenides CsV$_2$Se$_{2-x}$O (x = 0, 0.5). These compounds containing V$_2$O planar layers with a square lattice crystallize in the CeCr$_2$Si$_2$C structure with the space group of $P4/mmm$. ... More

Scrutinizing the double superconducting gaps and strong coupling pairing in (Li1-xFexOH)FeSeJun 15 2015Aug 05 2015In the iron based superconductors, one of the on-going frontier studies is about the pairing mechanism. The recent interest concerns the high temperature superconductivity and its intimate reason in the monolayer FeSe thin films. The challenge here is ... More

Sign reversal superconducting gaps revealed by phase referenced quasi-particle interference of impurity induced bound states in (Li$_{1-x}$Fe$_x$)OHFe$_{1-y}$Zn$_y$SeMar 28 2018By measuring the spatial distribution of differential conductance near impurities on Fe sites, we have obtained the quasi-particle interference (QPI) patterns in the (Li$_{1-x}$Fe$_x$)OHFe$_{1-y}$Zn$_y$Se superconductor with only electron Fermi surfaces. ... More

Highly anisotropic superconducting gap in underdoped Ba$_{1-x}$K$_x$Fe$_2$As$_2$May 11 2011The in-plane London penetration depth, $\Delta\lambda(T)$, was measured using a tunnel diode resonator in single crystals of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ for five doping levels $x$ ranging from underdoped, $T_c$=11 K ($x$=0.17), to optimally doped, $T_c=$38 ... More

Determination of the superconducting gap in near optimally doped Bi_2Sr_{2-x}La_xCuO_{6+δ} (x ~ 0.4) from low-temperature specific heatFeb 28 2011Low-temperature specific heat of the monolayer high-Tc superconductor Bi_2Sr_{2-x}La_xCuO_{6+\delta} has been measured close to the optimal doping point (x ~ 0.4) in different magnetic fields. The identification of both a T^2 term in zero field and a ... More

Transport properties and anisotropy of Rb0.8Fe2Se2 single crystalsDec 27 2010May 27 2011Single crystals of Rb{0.8}Fe2Se2 are successfully synthesized with the superconducting transition temperatures T_c{onset}= 31 K and T_c{zero}= 28 K. A clear anomaly of resistivity was observed in the normal state at about 150 K, as found in a similar ... More

Anisotropic Electronic Mobilities in the Nematic State of the Parent Phase NaFeAsMar 24 2015Hall effect and magnetoresistance have been measured on single crystals of the parent phase NaFeAs under a uniaxial pressure. Although significant difference of the in-plane resistivity $\rho_{xx}(I\parallel a)$ and $\rho_{xx}(I\parallel b)$ with the ... More

Vortex images on Ba{1-x}KxFe2As2 observed directly by the magnetic force microscopyDec 12 2011Jan 31 2012The vortex states on optimally doped Ba0.6K0.4Fe2As2 and underdoped Ba0.77K0.23Fe2As2 single crystals are imaged by magnetic force microscopy at various magnetic fields below 100 Oe. Local triangular vortex clusters are observed in optimally doped samples. ... More

Fully Gapped Superconducting State Based on a High Normal State Quasiparticle Density of States in Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ Single CrystalsAug 21 2008We report the specific heat (SH) measurements on single crystals of hole doped $FeAs$-based superconductor $Ba_{0.6}K_{0.4}Fe_2As_2$. It is found that the electronic SH coefficient $\gamma_e(T)$ is not temperature dependent and increases almost linearly ... More

Evidence for Two Gaps and Breakdown of the Uemura Plot in Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ Single CrystalsAug 06 2008Aug 07 2008We report a detailed investigation on the lower critical field $H_{c1}$ of the superconducting Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ (FeAs-122) single crystals. A pronounced kink is observed on the $H_{c1}(T)$ curve, which is attributed to the existence of ... More

General theory of sending-or-not-sending twin-field quantum key distributionApr 12 2019The Sending-or-Not-Sending (SNS) protocol of the twin-field quantum key distribution (TF-QKD) has its advantage of unconditional security proof under any coherent attack and fault tolerance to large misalignment error even considered finite-key effect. ... More

Magnetization relaxation, critical current density and vortex dynamics in a Ba$_{0.66}$K$_{0.32}$BiO$_{3+δ}$ single crystalMay 07 2015We have conducted extensive investigations on the magnetization and its dynamical relaxation on a Ba$_{0.66}$K$_{0.32}$BiO$_{3+\delta}$ single crystal. It is found that the magnetization relaxation rate is rather weak compared with that in the cuprate ... More

Superconductivity in Ti-doped Iron-Arsenide Compound Sr4Cr0.8Ti1.2O6Fe2As2Apr 06 2009Apr 10 2009Superconductivity was achieved in Ti-doped iron-arsenide compound Sr4Cr0.8Ti1.2O6Fe2As2 (abbreviated as Cr-FeAs-42622). The x-ray diffraction measurement shows that this material has a layered structure with the space group of \emph{P4/nmm}, and with ... More

Flux dynamics and vortex phase diagram in $Ba(Fe_{1-x}Co_x)_2As_2$ single crystals revealed by magnetization and its relaxationOct 19 2009Oct 21 2009Magnetization and its relaxation have been measured in $Ba(Fe_{1-x}Co_x)_2As_2$ single crystals at various doping levels ranging fromvery underdoped to very overdoped regimes. Sizable magnetization relaxation rate has been observed in all samples, indicating ... More

Synthesizing and characterization of hole doped nickel based superconductor (La$_{1-x}$Sr$_{x}$)NiAsOOct 08 2008We report the synthesizing and characterization of the hole doped Ni-based superconductor ($La_{1-x}Sr_{x})NiAsO$. By substituting La with Sr, the superconducting transition temperature $T_c$ is increased from 2.4 K of the parent phase $LaNiAsO$ to 3.7 ... More

Low temperature specific heat of the hole-doped Ba_{0.6}K_{0.4}Fe_2As_2 single crystals and electron-doped SmFeAsO_{0.9}F_{0.1} samplesDec 05 2008Low temperature specific heat (SH) was measured on the FeAs-based superconducting single crystals Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ and high pressure synthesized polycrystalline samples SmFeAsO$_{0.9}$F$_{0.1}$. It is found that the sharp SH anomaly $\Delta ... More

Superconductivity with two-fold symmetry in topological superconductor SrxBi2Se3Jul 21 2016Topological superconductivity is the quantum condensate of paired electrons with an odd parity of the pairing function. One of the candidates is the triplet pairing superconductor derived from topological insulator Bi2Se3 by chemical doping. Theoretically ... More

Distinct behaviors of suppression to superconductivity in $LaRu_3Si_2$ induced by Fe and Co dopantsFeb 24 2012In the superconductor LaRu$_3$Si$_2$ with the Kagome lattice of Ru, we have successfully doped the Ru with Fe and Co atoms. Contrasting behaviors of suppression to superconductivity is discovered between the Fe and the Co dopants: Fe-impurities can suppress ... More

General theory of sending-or-not-sending twin-field quantum key distributionApr 12 2019May 06 2019The Sending-or-Not-Sending (SNS) protocol of the twin-field quantum key distribution (TF-QKD) has its advantage of unconditional security proof under any coherent attack and fault tolerance to large misalignment error even considered finite-key effect. ... More

Superconductivity at 15.6 K in Calcium-doped Tb_{1-x}Ca_xFeAsO: the structure requirement for achieving superconductivity in the hole-doped 1111 phaseSep 30 2009Superconductivity at about 15.6 K was achieved in Tb_{1-x}Ca_xFeAsO by partially substituting Tb^{3+} with Ca^{2+} in the nominal doping region x = 0.40 \sim 0.50. A detailed investigation was carried out in a typical sample with doping level of x = 0.44. ... More

Tailoring the Superconductivity and Antiferromagnetic Order in SrFe2-xRhxAs2Mar 05 2009Mar 06 2009By doping Rh to the Fe sites in SrFe2As2, superconductivity is induced when the antiferromagnetic (AF) order is suppressed. The maximum superconducting transition temperature was found at about 22 K with the doping level of x = 0.25. It is found that ... More

Structural and transport properties of Sr2VO{3-delta}FeAs superconductors with different oxygen deficienciesOct 08 2009Oct 09 2009Sr2VO{3-delta}FeAs superconductors with different oxygen deficiencies have been successfully fabricated. It is found that the superconducting transition temperature drops down monotonically with the increase of oxygen deficiency. The diminishing of superconductivity ... More

Transition of stoichiometricSr2VO3FeAs to a superconducting state at 37.2 KApr 10 2009Aug 11 2009The superconductor Sr4V2O6Fe2As2 with transition temperature at 37.2 K has been fabricated. It has a layered structure with the space group of p4/nmm, and with the lattice constants a = 3.9296Aand c = 15.6732A. The observed large diamagnetization signal ... More

(Sr_3Sc_2O_5)Fe_2As_2 as a possible parent compound for FeAs-based superconductorsNov 13 2008Dec 17 2008A new compound with the FeAs-layers, namely (Sr_3Sc_2O_5)Fe_2As_2 (abbreviated as FeAs-32522), was successfully fabricated. It has a layered structure with the space group of I4/mmm, and with the lattice constants a = 4.069 $\AA$ and c = 26.876 $\AA$. ... More

Superconductivity in Fluorine-Arsenide Sr_{1-x}La_xFeAsFOct 14 2008Nov 06 2008Since the discovery of superconductivity\cite{1} at 26 K in oxy-pnictide $LaFeAsO_{1-x}F_x$, enormous interests have been stimulated in the fields of condensed matter physics and material sciences. Among the five different structures in this broad type ... More

SrFeAsF as a parent compound for iron pnictide superconductorsOct 14 2008Oct 30 2008We have successfully synthesized the fluo-arsenide SrFeAsF, a new parent phase with the ZrCuAsSi structure. The temperature dependence of resistivity and dc magnetization both reveal an anomaly at about T_{an} = 173 K, which may correspond to the structural ... More

Superconductivity at 25 K in hole doped $(La_{1-x}Sr_x)OFeAs$Mar 20 2008Mar 28 2008By partially substituting the tri-valence element La with di-valence element Sr in $LaOFeAs$, we introduced holes into the system. For the first time, we successfully synthesized the hole doped new superconductors $(La_{1-x}Sr_x)OFeAs$. The maximum superconducting ... More

Nodal Gap in Fe-Based Layered Superconductor LaO_0.9F_{0.1-delta}FeAs Probed by Specific Heat MeasurementsMar 06 2008Mar 07 2008We report the specific heat measurements on the newly discovered Fe-based layered superconductor LaO_0.9F_{0.1-delta}FeAs with the onset transition temperature T_c \approx 28 K. A nonlinear magnetic field dependence of the electronic specific heat coefficient ... More

Pressure Induced Enhancement of Superconductivity in LaRu2P2Apr 14 2015To explore new superconductors beyond the copper-based and iron-based systems is very important. The Ru element locates just below the Fe in the periodic table and behaves like the Fe in many ways. One of the common thread to induce high temperature superconductivity ... More

Discovery of a new nontoxic cuprate superconducting system Ga-Ba-Ca-Cu-OMay 23 2018Superconductivity is observed in a new nontoxic cuprate system Ga-Ba-Ca-Cu-O, with Tc = 82K for GaBa2Ca5Cu6O14+{\delta} (Ga-1256) and Tc = 116K probably for GaBa2Ca3Cu4O10+{\delta} (Ga-1234) or GaBa2Ca2Cu3O8+{\delta} (Ga-1223), respectively. All compounds ... More

Superconductivity induced by doping Platinum in BaFe2As2Jan 27 2010Apr 01 2010By substituting Fe with the 5d-transition metal Pt in BaFe2As2, we have successfully synthesized the superconductors BaFe2-xPtxAs2. The systematic evolution of the lattice constants indicates that the Fe ions were successfully replaced by Pt ions. By ... More

Upper critical field, anisotropy, and superconducting properties of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ single crystalsAug 18 2008Oct 06 2008The temperature dependent resistivity of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ (x = 0.23, 0.25, 0.28 and 0.4) single crystals and the angle dependent resistivity of superconducting Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystals were measured in magnetic fields ... More

Nodeless superconductivity in K$_x$Fe$_{2-y}$Se$_2$ single crystals revealed by low temperature specific heatJan 26 2011Low temperature specific heat (SH) has been measured in K$_x$Fe$_{2-y}$Se$_2$ single crystals with T$_c$ = 32 K. The SH anomaly associated with the superconducting transition is moderate and sharp yielding a value of $\Delta C/T \mid_{T_c}$ = 11.6 $\pm$ ... More

Discrete energy levels of Caroli-de Gennes-Martricon states in quantum limit due to small Fermi energy in FeTe$_{0.55}$Se$_{0.45}$Sep 27 2017Caroli-de Gennes-Martricon (CdGM) states were predicted in 1964 as low energy excitations within vortex cores of type-II superconductors. In the quantum limit, namely $T/T_\mathrm{c} \ll \Delta/E_\mathrm{F}$, the energy levels of these states were predicted ... More

BCS-like critical fluctuations with limited overlap of Cooper pairs in FeSeApr 28 2017Jul 14 2017In conventional superconductors, very narrow superconducting fluctuation regions are observed above $T_c$ because of the strong overlapping of Cooper pairs in a coherence volume. In the bulk form of iron chalcogenide superconductor FeSe, it is argued ... More

Pressure Tuned Enhancement of Superconductivity and Change of Ground State Properties in LaO0.5F0.5BiSe2 Single CrystalsJul 22 2014By using a hydrostatic pressure, we have successfully tuned the ground state and superconductivity in LaO0.5F0.5BiSe2 single crystals. It is found that, with the increase of pressure, the original superconducting phase with Tc about 3.5 K can be tuned ... More

Intrinsic Josephson junctions in the iron-based multi-band superconductor (V2Sr4O6)Fe2As2May 22 2014In layered superconductors, Josephson junctions may be formed within the unit cell due to sufficiently low interlayer coupling. These intrinsic Josephson junction (iJJ) systems have attracted considerable interest for their application potential in quantum ... More

Synthesis, structural and transport properties of the hole-doped Superconductor Pr_{1-x}Sr_xFeAsOOct 06 2008Jan 13 2009Superconductivity was achieved in PrFeAsO by partially substituting Pr^{3+} with Sr^{2+}. The electrical transport properties and structure of this new superconductor Pr_{1-x}Sr_xFeAsO at different doping levels (x = 0.05$\sim$ 0.25) were investigated ... More

Growth and characterization of A_{1-x}K_xFe_2As_2 (A = Ba, Sr) single crystals with x=0 - 0.4Jul 05 2008Oct 18 2008Single crystals of A$_{1-x}$K$_x$Fe$_2$As$_2$ (A=Ba, Sr) with high quality have been grown successfully by FeAs self-flux method. The samples have sizes up to 4 mm with flat and shiny surfaces. The X-ray diffraction patterns suggest that they have high ... More

Multi-Band Exotic Superconductivity in the New Superconductor Bi4O4S3Jul 20 2012Resistivity, Hall effect and magnetization have been investigated on the new superconductor Bi4O4S3. A weak insulating behavior has been induced in the normal state when the superconductivity is suppressed. Hall effect measurements illustrate clearly ... More

Synthesizing and characterization of hole doped nickel based layer superconductor (La$_{1-x}$Sr$_{x}$)ONiAsMar 27 2008Mar 29 2008We report the synthesizing and characterization of the hole doped Ni-based superconductor ($La_{1-x}Sr_{x})ONiAs$. By substituting La with Sr, the superconducting transition temperature $T_c$ is increased from 2.75 K of the parent phase $LaONiAs$ to 3.7 ... More

Point-Contact Spectroscopy of Iron-Based Layered Superconductor LaO$_{0.9}$F$_{0.1-δ}$FeAsMar 17 2008Aug 07 2008We present point-contact spectroscopy data for junctions between a normal metal and the newly discovered F-doped superconductor LaO$_{0.9}$F$_{0.1-\delta}$FeAs (F-LaOFeAs). A zero-bias conductance peak was observed and its shape and magnitude suggests ... More

Upper critical field, Hall effect and magnetoresistance in the iron-based layered superconductor LaFeAsO_{0.9}F_{0.1-δ}Mar 09 2008Jul 22 2008By using a two-step method, we successfully synthesized the iron based new superconductor LaFeAsO_{0.9}F_{0.1-\delta}$. The resistive transition curves under different magnetic fields were measured, leading to the determination of the upper critical field ... More

Magnetism and superconductivity in Sr$_2$VFeAsO$_3$ revealed by $^{75}$As- and $^{51}$V-NMR under elevated pressuresMay 13 2014We report $^{75}$As- and $^{51}$V-nuclear magnetic resonance (NMR) measurements on the iron-based superconductor Sr$_2$VFeAsO$_3$ with alternating stacks structure. We find that the $^{75}$As nuclear spin-spin relaxation rate ($1/T_2$) shows a pronounced ... More

Hall effect and magnetoresistance in single crystals of NdFeAsO$_{1-x}$F$_{x}$Jun 10 2008Sep 09 2008Hall effect and magnetoresistance have been measured on single crystals of $NdFeAsO_{1-x}F_{x}$ with x = 0 ($T_c$ = 0 $ $K) and x = 0.18 ($T_c$ = 50 $ $K). For the undoped samples, strong Hall effect and magnetoresistance with strong temperature dependence ... More

Collective vortex pinning and crossover between second order to first order transition in optimally doped Ba1-xKxBiO3 single crystalsJan 05 2017Measurements on magnetization and relaxation have been carried out on an optimally doped Ba$_{0.59}$K$_{0.47}$BiO$_{3+\delta}$ single crystal with $T_c$ = 31.3 K. Detailed analysis is undertaken on the data. Both the dynamical relaxation and conventional ... More

A hybrid structure gaseous detector for ion backflow suppression*Sep 26 2016Mar 31 2017A new concept for a hybrid structure gaseous detector module with ion backflow suppression for the time projection chamber in a future circular collider is presented. It is a hybrid structure cascaded Gas Electron Multiplier (GEM) with a Micromegas detector. ... More

Multiple Magnetization Peaks and New Type of Vortex Phase Transitions in Ba0.6K0.4Fe2As2Nov 25 2011Nov 30 2011Magnetization and its relaxation have been measured on Ba0.6K0.4Fe2As2 single crystals with Tc = 39 K. The magnetization hysteresis loops (MHLs) exhibit flux jumps in the low temperature region, and a second peak-effect in the intermediate temperature ... More

Strong coupling superconductivity and prominent superconducting fluctuations in the new superconductor Bi4O4S3Apr 11 2013Sep 16 2013Electric transport and scanning tunneling spectrum (STS) have been investigated on polycrystalline samples of the new superconductor Bi4O4S3. A weak insulating behavior in the resistive curve has been induced in the normal state when the superconductivity ... More

Merging Dirac electrons and correlation effect in the heterostructured Bi2Te3/Fe1+dTeSep 24 2015The topological insulator and strong electronic correlation effect are two important subjects in the frontier studies of modern condensed matter physics. A topological insulator exhibits a unique pair of surface conduction bands with the Dirac dispersion ... More

Sending-or-not twin-field quantum key distribution in practiceJul 25 2018We present results of practical sending-or-not quantum key distribution. In real-life implementations, we need consider the following three requirements, a few different intensities rather than infinite number of different intensities, a phase slice of ... More

Universality and unconventional enhancement of flux-flow resistivity in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$Dec 06 2016Measurements of the current-voltage characteristics were performed on Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystals with doping level $0.044 \leq x \leq 0.1$. An unconventional increase in the flux-flow resistivity $\rho_{\rm ff}$ with decreasing magnetic ... More

Path of Vowel Raising in Chengdu Dialect of MandarinMar 11 2018He and Rao (2013) reported a raising phenomenon of /a/ in /Xan/ (X being a consonant or a vowel) in Chengdu dialect of Mandarin, i.e. /a/ is realized as [epsilon] for young speakers but [ae] for older speakers, but they offered no acoustic analysis. We ... More

Accurate determination of the Fermi surface of tetragonal FeS via quantum oscillation measurements and quasiparticle self-consistent \textit{GW} calculationsSep 18 2018Feb 06 2019We perform de Haas-van Alphen measurements and quasiparticle self-consistent \textit{GW} (QS\textit{GW}) calculations on FeS. The calculated Fermi surface (FS) consists of two hole and two electron cylinders. We observe all the eight predicted FS cross ... More

Orbital-Selective Mottness in KxFe2-ySe2 Superconductors Revealed by Pump-Probe SpectroscopyJun 25 2013We report transient optical signatures of the orbital-selective Mottness in superconducting KxFe2-ySe2 crystals by using dual-color pump-probe spectroscopy. Besides multi-exponential decay recovery dynamics of photo-induced quasiparticles, a damped oscillatory ... More

Sign-reversal of the in-plane resistivity anisotropy in hole-doped iron pnictidesFeb 20 2012Apr 11 2013The in-plane anisotropy of the electrical resistivity across the coupled orthorhombic and magnetic transitions of the iron pnictides has been extensively studied in the parent and electron-doped compounds. All these studies universally show that the resistivity ... More

Transport properties and asymmetric scattering in Ba$_{1-x}$K$_x$Fe$_2$As$_2$ single crystals compared to the electron doped counterparts Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$}Jun 21 2011Nov 23 2011Resistivity, Hall effect and magnetoresistance have been investigated systematically on single crystals of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ ranging from undoped to optimally doped regions. A systematic evolution of the quasiparticle scattering has been observed. ... More

Anisotropic Superconducting Gap and Elongated Vortices with Caroli-De-Gennes-Matricon States in the New Superconductor Ta4Pd3Te16Dec 12 2014The superconducting state is formed by the condensation of a large number of Cooper pairs. The normal state electronic properties can give significant influence on the superconducting state. For usual type-II superconductors, the vortices are cylinder ... More

Angular dependence of resistivity in the superconducting state of NdFeAsO$_{0.82}$F$_{0.18}$ single crystalsJul 09 2008We report the results of angle dependent resistivity of NdFeAsO$_{0.82}$F$_{0.18}$ single crystals in the superconducting state. By doing the scaling of resistivity within the frame of the anisotropic Ginzburg-Landau theory, it is found that the angle ... More

Scaling of Hall Resistivity in the Mixed State of MgB2 FilmsJan 06 2008The longitudinal resistivity (rho_{xx}) and transverse resistivity (rho_{xy}) of MgB2 thin films in the mixed state were studied in detail. We found that the temperature dependencies of rho_{xx} and \rho_{xy} at a fixed magnetic field (H) satisfy the ... More

Fully gapped superconductivity in In-doped topological crystalline insulator Pb$_{0.5}$Sn$_{0.5}$TeMay 04 2015Superconductors derived from topological insulators and topological crystalline insulators by doping have long been considered to be candidates as topological superconductors. Pb$_{0.5}$Sn$_{0.5}$Te is a topological crystalline insulator with mirror symmetry ... More

Anomalous Properties in the Normal and Superconducting States of LaRu$_3$Si$_2$Sep 12 2011Superconductivity in LaRu$_3$Si$_2$ with the honeycomb structure of Ru atoms has been investigated. It is found that the normal state specific heat C/T exhibits a deviation from the Debye model down to the lowest temperature. A relation $C/T = \gamma_n+\beta ... More

Anisotropic resistivity in underdoped single crystals (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$, $0 \leq x<0.35$Jun 02 2011Temperature-dependent in-plane, $\rho_a(T)$, and inter-plane, $\rho_c(T)$, resistivities were measured for the iron-arsenide superconductor (Ba$_{1-x}$K$_x$)Fe $_2$As$_2$ over a broad doping range from parent compound to optimal doping $T_c\approx 38 ... More

Close relationship between superconductivity and the bosonic mode in Ba0.6K0.4Fe2As2 and Na(Fe0.975Co0.025)AsOct 30 2013Since the discovery of high temperature superconductivity in the iron pnictides and chalcogenides in early 2008, a central issue has been the microscopic origin of the superconducting pairing. Although previous experiments suggest that the pairing may ... More

Superconductivity at 22.3 K in SrFe2-xIrxAs2Feb 23 2009Feb 24 2009By substituting the Fe with the 5d-transition metal Ir in SrFe2As2, we have successfully synthesized the superconductor SrFe2-xIrxAs2 with Tc = 22.3 K at x = 0.5. X-ray diffraction indicates that the material has formed the ThCr2Si2-type structure with ... More

Impurity Scattering Effect on Superconductivity and the Violation of Anderson Theorem in Ba(Fe_{1-x}Co_x)_2As_2 Single CrystalsJun 24 2009Jun 30 2009Low-temperature specific heat (SH) and resistivity were measured on Ba(Fe_{1-x}Co_x)_2As_2 single crystals in wide doping region. A sizeable residual specific heat coefficient \gamma_0 was observed in the low temperature limit of all samples. The specific ... More

Reversible magnetization and critical fluctuations in systematically doped YBa$_2$Cu$_3$O$_{7-δ}$ single crystalsMar 29 2006Apr 03 2006The temperature and field dependence of reversible magnetization have been measured on a YBa$_2$Cu$_3$O$_{7-\delta}$ single crystal at six different doping concentrations. It is found that the data above 2 T can be described by the scaling law based on ... More

Low temperature specific heat of the 12442-type KCa_2Fe_4As_4F_2 single crystalsMar 22 2019Low-temperature specific heat (SH) is measured on the 12442-type KCa_2Fe_4As_4F_2 single crystal under different magnetic fields. A clear SH jump with the height \Delta C/T|_{T_c} = 130 mJ/mol K^2 was observed at the superconducting transition temperature ... More

Transport properties, upper critical field and anisotropy of Ba(Fe$_{0.75}$Ru$_{0.25}$)$_2$As$_2$ single crystalsMar 30 2012The temperature and angle dependent resistivity of Ba(Fe$_{0.75}$Ru$_{0.25}$)$_2$As$_2$ single crystals were measured in magnetic fields up to 14 T. The temperature dependent resistivity with the magnetic field aligned parallel to c-axis and ab-planes ... More

Raman-Scattering Detection of Nearly Degenerate $s$-Wave and $d$-Wave Pairing Channels in Iron-Based Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ and Rb$_{0.8}$Fe$_{1.6}$Se$_2$ SuperconductorsAug 24 2012Jul 27 2015We show that electronic Raman scattering affords a window into the essential properties of the pairing potential $V_{\mathbf{k},\mathbf{k^{\prime}}}$ of iron-based superconductors. In Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ we observe band dependent energy gaps ... More

Superconducting fluctuations in the reversible magnetization of the iron-pnictide $Ba_{1-x}K_xFe_2As_2$Feb 07 2009Jul 29 2009We report on isofield magnetization curves obtained as a function of temperature in two single crystals of $Ba_{1-x}K_xFe_2As_2$ with superconducting transition temperature $T_c$=28K and 32.7 K. Results obtained for fields above 20 kOe show a well defined ... More

In-Gap Quasiparticle Excitations Induced by Non-Magnetic Cu Impurities in Na(Fe0.96Co0.03Cu0.01)As Revealed by Scanning Tunneling SpectroscopyJun 09 2013Nov 20 2013The pairing mechanism in the iron pnictides remains unresolved yet. One of the central issues is the structure of the superconducting order parameter which classifies the community into two different and highly disputed camps. On one hand the picture ... More

Experimental Demonstration of the Sign Reversal of the Order Parameter in (Li1-xFex)OHFe1-yZnySeApr 20 2017Iron pnictides are the only known family of unconventional high-temperature superconductors besides cuprates. Until recently, it was widely accepted that superconductivity is spin-fluctuation driven and intimately related to their fermiology, specifically, ... More