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A non-abelian spin-liquid in a spin-1 quantum magnetDec 27 2010We study a time-reversal invariant non-abelian spin-liquid state in an $SU (2)$ symmetric spin $S = 1$ quantum magnet on a triangular lattice. The spin-liquid is obtained by quantum disordering a non-collinear nematic state. We show that such a spin-liquid ... More

Quantum spin nematics, dimerization, and deconfined criticality in quasi-one dimensional spin-1 magnetsJan 16 2007We study theoretically the destruction of spin nematic order due to quantum fluctuations in quasi-one dimensional spin-1 magnets. If the nematic ordering is disordered by condensing disclinations then quantum Berry phase effects induce dimerization in ... More

Cuprates as doped U(1) spin liquidsJun 02 2004We explore theoretically the notion that the underdoped cuprates may be viewed as doped U(1) spin liquid Mott insulators. We pursue a conceptually clear version of this idea that naturally incorporates several aspects of the phenomenology of the cuprates. ... More

On the mass enhancement near optimal doping in high magnetic fields in the cupratesOct 08 2014Recent observation of a mass enhancement in high magnetic fields in nearly optimally doped cuprates poses several puzzles. For the suggested nodal electron pocket induced by bidirectional charge order in high field, we propose that the mass enhancement ... More

Electron fractionalization and cuprate superconductivityMay 04 2001We discuss the possibility that the electron may be fractionalized in some quantum phases of matter in two or higher dimensions. We review the theory of such phases, and show that their effective theory is a $Z_2$ gauge theory. These phases may be characterized ... More

Pair density wave, charge density wave and vortex in high Tc cupratesFeb 08 2018A recent scanning tunneling microscopy (STM) experiment reports the observation of charge density wave (CDW) with period of approximately 8a in the halo region surrounding the vortex core, in striking contrast to the approximately period 4a CDW that are ... More

Theory of a continuous Mott transition in two dimensionsApr 09 2008We study theoretically the zero temperature phase transition in two dimensions from a Fermi liquid to a paramagnetic Mott insulator with a spinon Fermi surface. We show that the approach to the bandwidth controlled Mott transition from the metallic side ... More

Composite fermion duality for half-filled multicomponent Landau LevelsSep 27 2016We study the interplay of particle-hole symmetry and fermion-vortex duality in multicomponent half-filled Landau levels, such as quantum Hall gallium arsenide bilayers and graphene. For the $\nu{=}1/2{+}1/2$ bilayer, we show that particle-hole-symmetric ... More

Symmetry Protected Topological phases of Quantum MatterMay 15 2014We describe recent progress in our understanding of the interplay between interactions, symmetry, and topology in states of quantum matter. We focus on a minimal generalization of the celebrated topological band insulators to interacting many particle ... More

Critical fermi surfaces and non-fermi liquid metalsMar 28 2008Apr 07 2008At certain quantum critical points in metals an entire Fermi surface may disappear. A crucial question is the nature of the electronic excitations at the critical point. Here we provide arguments showing that at such quantum critical points the Fermi ... More

On non-Fermi liquid quantum critical points in heavy fermion metalsApr 10 2006Heavy electron metals on the verge of a quantum phase transition to magnetism show a number of unusual non-fermi liquid properties which are poorly understood. This article discusses in a general way various theoretical aspects of this phase transition ... More

Quantum matters: Physics beyond Landau's paradigmsNov 10 2004Central to our understanding of quantum many particle physics are two ideas due to Landau. The first is the notion of the electron as a well-defined quasiparticle excitation in the many body state. The second is that of the order parameter to distinguish ... More

Properties of the random field Ising model in a transverse magnetic fieldSep 15 1997We consider the effect of a random longitudinal field on the Ising model in a transverse magnetic field. For spatial dimension $d > 2$, there is at low strength of randomness and transverse field, a phase with true long range order which is destroyed ... More

A geometric proof of the equality between entanglement and edge spectraSep 06 2011The bulk-edge correspondence for topological quantum liquids states that the spectrum of the reduced density matrix of a large subregion reproduces the thermal spectrum of a physical edge. This correspondence suggests an intricate connection between ground ... More

Interacting fermionic topological insulators/superconductors in three dimensionsJan 06 2014May 29 2015Symmetry Protected Topological (SPT) phases are a minimal generalization of the concept of topological insulators to interacting systems. In this paper we describe the classification and properties of such phases for three dimensional(3D) electronic systems ... More

Time-reversal symmetric U(1) quantum spin liquidsMay 13 2015Mar 30 2016We study possible quantum $U(1)$ spin liquids in three dimensions with time-reversal symmetry. We find a total of 7 families of such $U(1)$ spin liquids, distinguished by the properties of their emergent electric/magnetic charges. We show how these spin ... More

Fractionalized gapless quantum vortex liquidsJul 28 2014May 12 2015The standard theoretical approach to gapless spin liquid phases of two-dimensional frustrated quantum antiferromagnets invokes the concept of fermionic slave particles into which the spin fractionalizes. As an alternate we explore new kinds of gapless ... More

Physics of low energy singlet states of the Kagome lattice quantum Heisenberg antiferromagnetMay 08 2003This paper is concerned with physics of the low energy singlet excitations found to exist below the spin gap in numerical studies of the Kagome lattice quantum Heisenberg antiferromagnet. Insight into the nature of these excitations is obtained by exploiting ... More

Physics of three dimensional bosonic topological insulators: Surface Deconfined Criticality and Quantized Magnetoelectric EffectSep 13 2012Jan 09 2013We discuss physical properties of `integer' topological phases of bosons in D=3+1 dimensions, protected by internal symmetries like time reversal and/or charge conservation. These phases invoke interactions in a fundamental way but do not possess topological ... More

Loop current order and d-wave superconductivity: some observable consequencesApr 25 2012May 02 2012Loop current order has been reported in the pseudogap regime of a few cuprate systems in polarized neutron scattering experiments. Here we study several observable consequences of such order in the d-wave superconducting state at low T. The symmetries ... More

Integer quantum Hall effect for bosons: A physical realizationJun 07 2012A simple physical realization of an integer quantum Hall state of interacting two dimensional bosons is provided. This is an example of a "symmetry-protected topological" (SPT) phase which is a generalization of the concept of topological insulators to ... More

Deconfined quantum criticality and Neel order via dimer disorderMay 31 2004Recent results on the nature of the quantum critical point between Neel and valence bond solid(VBS) ordered phases of two dimensional quantum magnets are examined by an attack from the VBS side. This approach leads to an appealingly simple physical description, ... More

Half-filled Landau level, topological insulator surfaces, and three dimensional quantum spin liquidsJul 29 2015Oct 07 2015We synthesize and partly review recent developments relating the physics of the half-filled Landau level in two dimensions to correlated surface states of topological insulators in three dimensions. The latter are in turn related to the physics of certain ... More

Dual Dirac liquid on the surface of the electron topological insulatorMay 19 2015Oct 06 2015We discuss a non-fermi liquid gapless metallic surface state of the topological band insulator. It has an odd number of gapless Dirac fermions coupled to a non-compact U(1) gauge field. This can be viewed as a vortex dual to the conventional Dirac fermion ... More

Fermi surfaces in general co-dimension and a new controlled non-trivial fixed pointJun 30 2008Traditionally Fermi surfaces for problems in $d$ spatial dimensions have dimensionality $d-1$, i.e., codimension $d_c=1$ along which energy varies. Situations with $d_c >1$ arise when the gapless fermionic excitations live at isolated nodal points or ... More

Zero temperature phase transitions in quantum Heisenberg ferromagnetsFeb 06 1996The purpose of this work is to understand the zero temperature phases, and the phase transitions, of Heisenberg spin systems which can have an extensive, spontaneous magnetic moment; this entails a study of quantum transitions with an order parameter ... More

Spin nematics and magnetization plateau transition in anisotropic Kagome magnetsFeb 28 2006We study S=1 kagome antiferromagnets with isotropic Heisenberg exchange $J$ and strong easy axis single-ion anisotropy $D$. For $D \gg J$, the low-energy physics can be described by an effective $S=1/2$ $XXZ$ model with antiferromagnetic $J_z \sim J$ ... More

Microscopic models for fractionalized phases in strongly correlated systemsJan 17 2002We construct explicit examples of microscopic models that stabilize a variety of fractionalized phases of strongly correlated systems in spatial dimension bigger than one, and in zero external magnetic field. These include models of charge fractionalization ... More

Universal crossovers between entanglement entropy and thermal entropyDec 05 2011We postulate the existence of universal crossover functions connecting the universal parts of the entanglement entropy to the low temperature thermal entropy in gapless quantum many-body systems. These scaling functions encode the intuition that the same ... More

Chiral RKKY interaction in Pr2Ir2O7Jan 04 2013Motivated by the potential chiral spin liquid in the metallic spin ice Pr2Ir2O7, we consider how such a chiral state might be selected from the spin ice manifold. We propose that chiral fluctuations of the conducting Ir moments promote ferro-chiral couplings ... More

Fractionalization, topological order, and quasiparticle statisticsJun 01 2005Nov 29 2005We argue, based on general principles, that topological order is essential to realize fractionalization in gapped insulating phases in dimensions $d \geq 2$. In $d=2$ with genus $g$, we derive the existence of the minimum topological degeneracy $q^g$ ... More

Twisted Hubbard Model for Sr2IrO4: Magnetism and Possible High Temperature SuperconductivityNov 15 2010Nov 17 2010Sr2IrO4 has been suggested as a Mott insulator from a single J_eff=1/2 band, similar to the cuprates. However this picture is complicated by the measured large magnetic anisotropy and ferromagnetism. Based on a careful mapping to the J_eff=1/2 (pseudospin-1/2) ... More

Boson topological insulators: A window into highly entangled quantum phasesFeb 25 2013May 07 2013We study several aspects of the realization of global symmetries in highly entangled phases of quantum matter. Examples include gapped topological ordered phases, gapless quantum spin liquids and non-fermi liquid phases. An insightful window into such ... More

Wave Functions of Bosonic Symmetry Protected Topological PhasesJan 25 2013Apr 28 2013We study the structure of the ground state wave functions of bosonic Symmetry Protected Topological (SPT) insulators in 3 space dimensions. We demonstrate that the differences with conventional insulators are captured simply in a dual vortex description. ... More

On the stability of U(1) spin liquids in two dimensionsApr 30 2004Oct 14 2004We establish that spin liquids described in terms of gapless fermionic (Dirac) spinons and gapless U(1) gauge fluctuations can be stable in two dimensions, at least when the physical SU(2) spin symmetry is generalized to SU(N). Equivalently, we show that ... More

Probing Hidden Orders with Resonant Inelastic X-Ray ScatteringJun 15 2015We propose a general scheme for the derivation of the signals resonant inelastic (and elastic) x-ray scattering (RIXS) gives access to. In particular, we find that RIXS should allow to directly detect many hidden orders, such as spin nematic, bond nematic, ... More

Microscopic model for the boson integer quantum Hall effectMay 01 2013In two dimensions strongly interacting bosons in a magnetic field can form an integer quantum Hall state. This state has a bulk gap, no fractional charges or topological order in the bulk but nevertheless has quantized Hall transport and symmetry protected ... More

Higher angular momentum Kondo liquidsNov 29 2006Conventional heavy Fermi liquid phases of Kondo lattices involve the formation of a "Kondo singlet" between the local moments and the conduction electrons. This Kondo singlet is usually taken to be in an internal s-wave angular momentum state. Here we ... More

Neel order, quantum spin liquids and quantum criticality in two dimensionsSep 02 2005Sep 22 2005This paper is concerned with the possibility of a direct second order transition out of a collinear Neel phase to a paramagnetic spin liquid in two dimensional quantum antiferromagnets. Contrary to conventional wisdom, we show that such second order quantum ... More

Luttinger Liquid Physics in the Superconductor Vortex CoreJan 01 2000May 26 2000We study several aspects of the structure of vortices in conventional s-wave Type $II$ superconductors. It is well-known that there are low energy quasiparticles bound to the core of a vortex. We show that under certain conditions, these quasiparticles ... More

Lattice models for non-Fermi liquid metalsSep 04 2008Dec 29 2008We present two 2D lattice models with non-Fermi liquid metallic phases. We show that the low energy physics of these models is exactly described by a Fermi sea of fractionalized quasiparticles coupled to a fluctuating U(1) gauge field. In the first model, ... More

Quantum phase transition from an antiferromagnet to a spin liquid in a metalOct 07 2009We study quantum phase transitions from easy-plane antiferromagnetic metals to paramagnetic metals in Kondo-Heisenberg lattice systems. If the paramagnetic metal is a fractionalized Fermi liquid then the universal critical properties of the phase transition ... More

Dimensional decoupling at continuous quantum critical Mott transitionsMar 30 2016Jul 30 2016For continuous Mott metal-insulator transitions in layered two dimensional systems, we demonstrate the phenomenon of dimensional decoupling: the system behaves as a three-dimensional metal in the Fermi liquid side but as a stack of decoupled two-dimensional ... More

Theory of the Kagome Lattice Ising Antiferromagnet in Weak Transverse FieldFeb 09 2004We study the quantum Ising antiferromagnet on the Kagome lattice, with weak transverse field dynamics and other local perturbations. We analytically demonstrate the possibility of a disordered zero-temperature phase that is smoothly connected to the phase ... More

Entanglement Entropy of U(1) Quantum Spin LiquidsOct 13 2015We here investigate the entanglement structure of the ground state of a (3+1)-dimensional U(1) quantum spin liquid, which is described by the deconfined phase of a compact U(1) gauge theory. A gapless photon is the only low-energy excitation, with matter ... More

Entanglement Structure of Deconfined Quantum Critical PointsSep 14 2011We study the entanglement properties of deconfined quantum critical points. We show not only that these critical points may be distinguished by their entanglement structure but also that they are in general more highly entangled that conventional critical ... More

Spontaneous interlayer coherence in bilayer Kondo systemsNov 25 2004Mar 16 2005Bilayer Kondo systems present interesting models to illustrate the competition between the Kondo effect and intermoment exchange. Such bilayers can exhibit two sharply distinct Fermi liquid phases which are distinguished by whether or not the local moments ... More

Higher dimensional realizations of activated dynamic scaling at random quantum transitionsSep 03 1996We show that many of the unusual properties of the one-dimensional random quantum Ising model are shared also by dilute quantum Ising systems in the vicinity of a certain quantum transition in {\em any} dimension $d > 1$. Thus, while these properties ... More

Composite fermi liquids in the lowest Landau levelApr 22 2016Jul 25 2016We study composite fermi liquid (CFL) states in the lowest Landau level (LLL) limit at a generic filling $\nu = \frac{1}{n}$. We begin with the old observation that, in compressible states, the composite fermion in the lowest Landau level should be viewed ... More

Topological spin Hall states, charged skyrmions, and superconductivity in two dimensionsJan 14 2008Jan 17 2008We study the properties of two dimensional topological spin hall insulators which arise through spontaneous breakdown of spin symmetry in systems that are spin rotation invariant. Such a phase breaks spin rotation but not time reversal symmetry and has ... More

On the origin of artificial electrodynamics and other stories in three-dimensional bosonic modelsJul 14 2004Several simple models of strongly correlated bosons on three-dimensional lattices have been shown to possess exotic fractionalized Mott insulating phases with a gapless `photon' excitation. In this paper we show how to view the physics of this `Coulomb' ... More

Spin and pair density wave glassesJan 30 2015Spontaneous breaking of translational symmetry---known as `density wave' order---is common in nature. However such states are strongly sensitive to impurities or other forms of frozen disorder leading to fascinating glassy phenomena. We analyze impurity ... More

Theory of a continuous stripe melting transition in a two dimensional metal: Possible application to cupratesJan 16 2012Jan 25 2012We develop a concrete theory of continuous stripe melting quantum phase transitions in two dimensional metals and the associated Fermi surface reconstruction. Such phase transitions are strongly coupled but yet theoretically tractable in situations where ... More

Stripe melting and quantum criticality in correlated metalsJul 05 2012We study theoretically quantum melting transitions of stripe order in a metallic environment, and the associated reconstruction of the electronic Fermi surface. We show that such quantum phase transitions can be continuous in situations where the stripe ... More

A synthesis of the phenomenology of the underdoped cupratesMar 05 2009Mar 14 2009The underdoped cuprates have a number of interesting and unusual properties that often seem hard to reconcile with one another. In this paper we show how many of these diverse phenomena can be synthesized into a single coherent theoretical picture. Specifically ... More

Projected wave functions for fractionalized phases of quantum spin systemsApr 02 2002Gutzwiller projection allows a construction of an assortment of variational wave functions for strongly correlated systems. For quantum spin S=1/2 models, Gutzwiller-projected wave functions have resonating-valence-bond structure and may represent states ... More

Coherence and pairing in a doped Mott insulator: Application to the cupratesApr 08 2009The issues of single particle coherence and its interplay with singlet pairing are studied within the slave boson gauge theory of a doped Mott insulator. Prior work by one of us (T. Senthil, arXiv:0804.1555) showed that the coherence scale below which ... More

Decohering the Fermi liquid: A dual approach to the Mott TransitionJul 20 2011We present a theoretical approach to describing the Mott transition of electrons on a two dimensional lattice that begins with the low energy effective theory of the Fermi liquid. The approach to the Mott transition must be characterized by the suppression ... More

Exotic order in simple models of bosonic systemsMay 08 2002We show that simple Bose Hubbard models with unfrustrated hopping and short range two-body repulsive interactions can support stable fractionalized phases in two and higher dimensions, and in zero magnetic field. The simplicity of the constructed models ... More

Charge Friedel oscillations in a Mott insulatorJul 14 2010When a metal undergoes a transition to an insulator it will lose its electronic Fermi surface. Interestingly in some situations a `ghost' Fermi surface of electrically neutral spin carrying fermions may survive into the insulator. Such a novel ghost Fermi ... More

Critical Properties of Random Quantum Potts and Clock ModelsNov 24 1995We study zero temperature phase transitions in two classes of random quantum systems -the $q$-state quantum Potts and clock models. For models with purely ferromagnetic interactions in one dimension, we show that for strong randomness there is a second ... More

Gapped Symmetry Preserving Surface-State for the Electron Topological InsulatorJun 13 2013May 16 2014It is well known that the 3D electronic topological insulator (TI) with charge-conservation and time-reversal symmetry cannot have a trivial insulating surface that preserves symmetry. It is often implicitly assumed that if the TI surface preserves both ... More

Universal Magnetic Properties of Frustrated Quantum Antiferromagnets in Two DimensionsNov 18 1993We present a theory of frustrated, two-dimensional, quantum antiferromagnets in the vicinity of a quantum transition from a non-collinear, magnetically-ordered ground state to a quantum-disordered phase. Using a sigma-model for bosonic, spin-1/2, spinon ... More

Finite temperature properties of quantum Lifshitz transitions between valence bond solid phases: An example of `local' quantum criticalityDec 15 2004We study the finite temperature properties of quantum magnets close to a continuous quantum phase transition between two distinct valence bond solid phases in two spatial dimension. Previous work has shown that such a second order quantum `Lifshitz' transition ... More

Design and Analysis of SD_DWCA - A Mobility based clustering of Homogeneous MANETsMay 27 2011This paper deals with the design and analysis of the distributed weighted clustering algorithm SD_DWCA proposed for homogeneous mobile ad hoc networks. It is a connectivity, mobility and energy based clustering algorithm which is suitable for scalable ... More

Fractionalized Fermi liquidsSep 05 2002May 07 2003In spatial dimensions d >= 2, Kondo lattice models of conduction and local moment electrons can exhibit a fractionalized, non-magnetic state (FL*) with a Fermi surface of sharp electron-like quasiparticles, enclosing a volume quantized by (\rho_a-1)(mod ... More

Quantum Confinement Transition and Cuprate CriticalityDec 21 1999Theoretical attempts to explain the origin of high temperature superconductivity are challenged by the complexity of the normal state, which exhibits three regimes with increasing hole doping: a pseudo-gap regime when underdoped, strange power laws near ... More

Topological Paramagnetism in Frustrated Spin-One Mott InsulatorsJan 06 2015Time reversal protected three dimensional (3D) topological paramagnets are magnetic analogs of the celebrated 3D topological insulators. Such paramagnets have a bulk gap, no exotic bulk excitations, but non-trivial surface states protected by symmetry. ... More

Angle dependent quasiparticle weights in correlated metalsOct 12 2007The variation in the quasiparticle weight $Z$ on moving around the fermi surface in correlated metals is studied theoretically. Our primary example is a heavy Fermi liquid treated within the standard hybridization mean field theory. The most dramatic ... More

Weak magnetism and non-Fermi liquids near heavy-fermion critical pointsMay 08 2003Oct 13 2003This paper is concerned with the weak-moment magnetism in heavy-fermion materials and its relation to the non-Fermi liquid physics observed near the transition to the Fermi liquid. We explore the hypothesis that the primary fluctuations responsible for ... More

A Multi-Hop Weighted Clustering of Homogenous MANETs Using Combined Closeness IndexApr 29 2011In this paper, a new multi-hop weighted clustering procedure is proposed for homogeneous Mobile Ad hoc networks. The algorithm generates double star embedded non-overlapping cluster structures, where each cluster is managed by a leader node and a substitute ... More

Quantum Criticality and Deconfinement in Phase Transitions Between Valence Bond SolidsNov 04 2003May 29 2004We consider spin-half quantum antiferromagnets in two spatial dimensions in the quantum limit, where the spins are in a valence bond solid (VBS) phase. The transitions between two such VBS phases is studied. In some cases, an interesting second order ... More

Fractionalization, topological order, and cuprate superconductivityAug 05 2000This paper is concerned with the idea that the electron is fractionalized in the cuprate high-$T_c$ materials. We show how the notion of topological order may be used to develop a precise theoretical characterization of a fractionalized phase in spatial ... More

Detecting fractions of electrons in the high-$T_c$ cupratesNov 21 2000We propose several tests of the idea that the electron is fractionalized in the underdoped and undoped cuprates. These include the ac Josephson effect, and tunneling into small superconducting grains in the Coulomb blockade regime. In both cases, we argue ... More

Orthogonal Metals: The simplest non-Fermi liquidsJan 28 2012Apr 03 2012We present a fractionalized metallic phase which is indistinguishable from the Fermi liquid in conductivity and thermodynamics, but is sharply distinct in one electron properties, such as the electron spectral function. We dub this phase the `Orthogonal ... More

Quantum phase transitions out of the heavy Fermi liquidSep 01 2004Oct 20 2004We review recent work on the instability of the heavy Fermi liquid state (FL) of the Kondo lattice towards a magnetic metal in which the local moments are not part of the Fermi sea. Using insights drawn from the theory of deconfined quantum criticality ... More

Classification of interacting electronic topological insulators in three dimensionsJun 13 2013Nov 13 2013A fundamental open problem in condensed matter physics is how the dichotomy between conventional and topological band insulators is modified in the presence of strong electron interactions. We show that there are 6 new electronic topological insulators ... More

Superfluid Insulator Transitions of Hard-Core Bosons on the Checkerboard LatticeJan 19 2007Mar 29 2008We study hard-core bosons on the checkerboard lattice with nearest neighbour unfrustrated hopping $t$ and `tetrahedral' plaquette charging energy $U$. Analytical arguments and Quantum Monte Carlo simulations lead us to the conclusion that the system undergoes ... More

Fractionalization and confinement in the U(1) and $Z_2$ gauge theories of strongly correlated systemsJun 30 2000Recently, we have elucidated the physics of electron fractionalization in strongly interacting electron systems using a $Z_2$ gauge theory formulation. Here we discuss the connection with the earlier U(1) gauge theory approaches based on the slave boson ... More

Z_2 Gauge Theory of Electron Fractionalization in Strongly Correlated SystemsOct 15 1999Oct 21 1999We develop a new theoretical framework for describing and analyzing exotic phases of strongly correlated electrons which support excitations with fractional quantum numbers. Starting with a class of microscopic models believed to capture much of the essential ... More

Quasiparticle density of states in dirty high-T_c superconductorsOct 20 1998We study the density of quasiparticle states of dirty d-wave superconductors. We show the existence of singular corrections to the density of states due to quantum interference effects. We then argue that the density of states actually vanishes in the ... More

Quasiparticle localization in superconductors with spin-orbit scatteringJun 17 1999We develop a theory of quasiparticle localization in superconductors in situations without spin rotation invariance. We discuss the existence, and properties of superconducting phases with localized/delocalized quasiparticle excitations in such systems ... More

Competing orders, non-linear sigma models, and topological terms in quantum magnetsOct 18 2005A number of examples have demonstrated the failure of the Landau-Ginzburg-Wilson(LGW) paradigm in describing the competing phases and phase transitions of two dimensional quantum magnets. In this paper we argue that such magnets possess field theoretic ... More

Quantum Phase Transition in Frustrated Two-Dimensional AntiferromagnetsFeb 02 1994We study frustrated, two-dimensional, quantum antiferromagnets in the vicinity of a quantum transition from a non-collinear, magnetically-ordered ground state to a quantum disordered phase. The general scaling properties of this transition are described. ... More

Exotic S=1 spin liquid state with fermionic excitations on triangular latticeAug 15 2011Aug 22 2011Motivated by recent experiments on the material Ba_3NiSb_2O_9 we consider a spin-one quantum antiferromagnet on a triangular lattice with the Heisenberg bilinear and biquadratic exchange interactions and a single-ion anisotropy. Using a fermionic "triplon" ... More

Possible ferro-spin nematic order in NiGa2S4May 10 2006We explore the possibility that the spin-1 triangular lattice magnet NiGa2 S4 may have a ferro-nematic ground state with no frozen magnetic moment but a uniform quadrupole moment. Such a state may be stabilized by biquadratic spin interactions. We describe ... More

Finite Temperature Properties of Quantum Antiferromagnets in a Uniform Magnetic Field in One and Two DimensionsJan 19 1994Consider a $d$-dimensional antiferromagnet with a quantum disordered ground state and a gap to bosonic excitations with non-zero spin. In a finite external magnetic field, this antiferromagnet will undergo a phase transition to a ground state with non-zero ... More

Fractionalization in the cuprates: Detecting the topological orderJun 30 2000The precise theoretical characterization of a fractionalized phase in spatial dimensions higher than one is through the concept of ``topological order''. We describe a physical effect that is a robust and direct consequence of this hidden order that should ... More

Overscreened Kondo fixed point in S=1 spin liquidDec 20 2012We propose a possible realization of the overscreened Kondo impurity problem by a magnetic s=1/2 impurity embedded in a two-dimensional S=1 U(1) spin liquid with a Fermi surface. This problem contains an interesting interplay between non-Fermi-liquid ... More

Kondo Vortices, Zero Modes, and Magnetic Ordering in a Kondo Lattice ModelMar 25 2009Motivated by the mysteries of the heavy fermion quantum critical point, we investigate the competition between Kondo screening and magnetic ordering in the honeycomb Kondo lattice at half filling. We examine the destruction of the Kondo phase by proliferating ... More

Screening and Dissipation at the Superconductor-Insulator Transition Induced by a Metallic Ground PlaneSep 04 2002We study localization phenomena in two dimensional systems of charged particles in the presence of a metallic ground plane with a particular focus on the superconductor-insulator transition. The ground plane introduces a screening of the long-range Coulomb ... More

Liouville Numbers and Schanuel's ConjectureDec 26 2013In this paper, using an argument of P. Erdos, K. Alniacik and E. Saias, we extend earlier results on Liouville numbers, due to P. Erdos, G.J. Rieger, W. Schwarz, K. Alniacik, E. Saias, E.B. Burger. We also produce new results of algebraic independence ... More

Universal transport near a quantum critical Mott transition in two dimensionsJun 14 2012Jan 15 2013We discuss the universal transport signatures near a zero-temperature continuous Mott transition between a Fermi liquid (FL) and a quantum spin liquid in two spatial dimensions. The correlation-driven transition occurs at fixed filling and involves fractionalization ... More

Mott transition between a spin-liquid insulator and a metal in three dimensionsNov 13 2008Dec 01 2008We study a bandwidth controlled Mott metal-insulator transition (MIT) between a Fermi liquid metal and a quantum spin-liquid insulator at half-filling in three dimensions (3D). Using a slave rotor approach, and incorporating gauge field fluctuations, ... More

Quantum spin liquids and the metal-insulator transition in doped semiconductorsApr 05 2012Apr 10 2012We describe a new possible route to the metal-insulator transition in doped semiconductors such as Si:P or Si:B. We explore the possibility that the loss of metallic transport occurs through Mott localization of electrons into a quantum spin liquid state ... More

Algebraic spin liquid as the mother of many competing ordersFeb 08 2005Jul 25 2005We study the properties of a class of two-dimensional interacting critical states -- dubbed algebraic spin liquids -- that can arise in two-dimensional quantum magnets. A particular example that we focus on is the staggered flux spin liquid, which plays ... More

Amperean Pairing Instability in the U(1) Spin Liquid State with Fermi Surface and Application to $κ-(BEDT-TTF)_2 Cu_2 (CN)_3$Jul 01 2006Recent experiments on the organic compound $\kappa-(BEDT-TTF)_2 Cu_2 (CN)_3$ raise the possibility that the system may be described as a quantum spin liquid. Here we propose a pairing state caused by the `Amperean' attractive interaction between spinons ... More

A Duality Web in 2+1 Dimensions and Condensed Matter PhysicsJun 07 2016Jul 27 2016Building on earlier work in the high energy and condensed matter communities, we present a web of dualities in $2+1$ dimensions that generalize the known particle/vortex duality. Some of the dualities relate theories of fermions to theories of bosons. ... More

A controlled expansion for certain non-Fermi liquid metalsMar 04 2010The destruction of Fermi liquid behavior when a gapless Fermi surface is coupled to a fluctuating gapless boson field is studied theoretically. This problem arises in a number of different contexts in quantum many body physics. Examples include fermions ... More

Erratum: algebraic spin liquid as the mother of many competing ordersSep 19 2007We correct an error in our paper Phys. Rev. B 72, 104404 (2005) [cond-mat/0502215]. We show that a particular fermion bilinear is not related to the other ``competing orders'' of the algebraic spin liquid, and does not possess their slowly decaying correlations. ... More