Magnetothermoelectric Response near Quantum Critical Points (2008)
Bhaseen, M. J., Green, A. G., Sondhi, S. L.
Following on from our previous work [Phys. Rev. Lett. 98, 166801 (2007)] we examine the finite temperature magnetothermoelectric response in the vicinity of a quantum critical point (QCP). We begin...
Quantum dimer models and exotic orders (2008)
Raman, K. S., Fradkin, E., Moessner, R., Papanikolaou, S., Sondhi, S. L.
We discuss how quantum dimer models may be used to provide "proofs of principle" for the existence of exotic magnetic phases in quantum spin systems.
Monopole Flux State on the Pyrochlore Lattice (2008)
Burnell, F. J., Chakravarty, Shoibal, Sondhi, S. L.
The ground state of a spin 1/2 nearest neighbor quantum Heisenberg antiferromagnet on the pyrochlore lattice is investigated using a large $N$ SU(N) fermionic mean field theory. We find several mean...
Order and Disorder in AKLT Antiferromagnets in Three Dimensions (2008)
Parameswaran, Siddharth A., Sondhi, S. L., Arovas, Daniel P.
The models constructed by Affleck, Kennedy, Lieb, and Tasaki describe a family of quantum antiferromagnets on arbitrary lattices, where the local spin S is an integer multiple M of half the lattice...
Flux Hamiltonians, Lie Algebras and Root Lattices With Minuscule Decorations (2008)
Shankar, R., Burnell, F. J., Sondhi, S. L.
We study a family of Hamiltonians of fermions hopping on a set of lattices in the presence of a background gauge field. The lattices are constructed by decorating the root lattices of various Lie...
Classical Antiferromagnetism on Torquato-Stillinger Packings (2008)
Torquato and Stillinger have constructed a new family of frustrated lattices by unusually high dilution of close packed structures while preserving structural stability. We show that an infinite...
Laumann, C., Scardicchio, A., Sondhi, S. L.
We study the diluted Ising ferromagnet on the Bethe lattice as a case study for the application of the cavity method to problems with Griffiths-McCoy singularities. Specifically, we are able to make...
Cavity method for quantum spin glasses on the Bethe lattice (2007)
Laumann, C., Scardicchio, A., Sondhi, S. L.
We propose a generalization of the cavity method to quantum spin glasses on fixed connectivity lattices. Our work is motivated by the recent refinements of the classical technique and its potential...
Resonating singlet valence plaquettes (2007)
Pankov, S., Moessner, R., Sondhi, S. L.
We consider the simplest generalizations of the valence bond physics of SU(2) singlets to SU(N) singlets that comprise objects with N sites -- these are SU(N) singlet plaquettes with N=3 and N=4 in...
Magnetothermoelectric Response at a Superfluid--Mott Insulator Transition (2006)
Bhaseen, M. J., Green, A. G., Sondhi, S. L.
We investigate the finite temperature magnetothermoelectric response in the vicinity of a superfluid--Mott insulator quantum phase transition. We focus on the particle-hole symmetric transitions of...
Current fluctuations near to the 2D superconductor-insulator quantum critical point (2006)
Green, A. G., Moore, J. E., Sondhi, S. L., Vishwanath, A.
Systems near to quantum critical points show universal scaling in their response functions. We consider whether this scaling is reflected in their fluctuations; namely in current-noise. Naive scaling...
Spin-nematic order in the frustrated pyrochlore-lattice quantum rotor model (2005)
Gregor, Karol, Huse, David A., Sondhi, S. L.
As an example of ordering due to quantum fluctuations, we examine the nearest-neighbor antiferromagnetic quantum O(n) rotor model on the pyrochlore lattice. Classically, this system remains...
From exotic phases to microscopic Hamiltonians (2005)
Moessner, R., Raman, K. S., Sondhi, S. L.
We report recent analytical progress in the quest for spin models realising exotic phases. We focus on the question of `reverse-engineering' a local, SU(2) invariant S=1/2 Hamiltonian to exhibit...
Quantum dimer models and effective Hamiltonians on the pyrochlore lattice (2005)
Moessner, R., Sondhi, S. L., Goerbig, M. O.
We study a large-N deformation of the S=1/2 pyrochlore Heisenberg antiferromagnet which leads to a soluble quantum dimer model at leading non-trivial order. In this limit, the ground state manifold...
On the magnetization of two-dimensional superconductors (2005)
Oganesyan, Vadim, Huse, David A., Sondhi, S. L.
We calculate the magnetization of a two-dimensional superconductor in a perpendicular magnetic field near its Kosterlitz-Thouless transition and at lower temperatures. We find that the critical...
Why spin ice obeys the ice rules (2005)
Isakov, S. V., Moessner, R., Sondhi, S. L.
The low temperature entropy of the the spin ice compounds, such as Ho$_2$Ti$_2$O$_7$ and Dy$_2$Ti$_2$O$_7$, is well described by the nearest-neighbor antiferromagnetic Ising model on the pyrochlore...
SU(2)-invariant spin-1/2 Hamiltonians with RVB and other valence bond phases (2005)
Raman, K. S., Moessner, R., Sondhi, S. L.
We construct a family of rotationally invariant, local, S=1/2 Klein Hamiltonians on various lattices that exhibit ground state manifolds spanned by nearest-neighbor valence bond states. We show that...
Non-linear quantum critical transport and the Schwinger Mechanism (2005)
Scaling arguments imply that quantum critical points exhibit universal non-linear responses to external probes. We investigate the origins of such non-linearities in transport, which is especially...
Critical scaling of thermal transport in model A dynamics for a superconductor (2004)
Ussishkin, Iddo, Huse, David A., Sondhi, S. L.
We consider the scaling of thermal transport in the presence of electric and magnetic fields near the finite temperature transition from the metallic normal state to the superconductor. We do so with...
Flux expulsion and greedy bosons: frustrated magnets at large N (2004)
Tchernyshyov, O., Moessner, R., Sondhi, S. L.
We investigate the Sp(N) mean-field theory for frustrated quantum magnets. First, we establish some general properties of its solutions; in particular, for small spin we propose simple rules for...
Dipolar spin correlations in classical pyrochlore magnets (2004)
Isakov, S. V., Gregor, K., Moessner, R., Sondhi, S. L.
We study spin correlations for the highly frustrated classical pyrochlore lattice antiferromagnets with O(N) symmetry in the limit T->0. We conjecture that a local constraint obeyed by the...
On the interpretation of the Nernst effect measurements in the cuprates (2004)
Ussishkin, Iddo, Sondhi, S. L.
We consider the large Nernst signal discovered by Ong and collaborators in hole-doped cuprates, in particular in the pseudogap regime. Based on our previous quantitative calculations together with...
Magnetization process of spin ice in a [111] magnetic field (2004)
Isakov, S. V., Raman, K. S., Moessner, R., Sondhi, S. L.
Spin ice in a magnetic field in the [111] direction displays two magnetization plateaux, one at saturation and an intermediate one with finite entropy. We study the crossovers between the different...
Superconductors are topologically ordered (2004)
Hansson, T. H., Oganesyan, Vadim, Sondhi, S. L.
We revisit a venerable question: what is the nature of the ordering in a superconductor? We find that the answer is properly that the superconducting state exhibits topological order in the sense of...
On bipartite Rokhsar-Kivelson points and Cantor deconfinement (2003)
Fradkin, Eduardo, Huse, David A., Moessner, R., Oganesyan, V., Sondhi, S. L.
Quantum dimer models on bipartite lattices exhibit Rokhsar-Kivelson (RK) points with exactly known critical ground states and deconfined spinons. We examine generic, weak, perturbations around these...
Three dimensional resonating valence bond liquids and their excitations (2003)
We show that there are two types of RVB liquid phases present in three-dimensional quantum dimer models, corresponding to the deconfining phases of U(1) and Z_2 gauge theories in d=3+1. The former is...
Coulomb and Liquid Dimer Models in Three Dimensions (2003)
Huse, David A., Krauth, Werner, Moessner, R., Sondhi, S. L.
We study classical hard-core dimer models on three-dimensional lattices using analytical approaches and Monte Carlo simulations. On the bipartite cubic lattice, a local gauge field generalization of...
Theory of the [111] magnetization plateau in spin ice (2003)
The application of a magnetic field along the [111] direction in the spin ice compounds leads to two magnetization plateaux, in the first of which the ground state entropy is reduced but still...
On Ising and dimer models in two and three dimensions (2002)
Motivated by recent interest in 2+1 dimensional quantum dimer models, we revisit Fisher's mapping of two dimensional Ising models to hardcore dimer models. First, we note that the symmetry breaking...
A Farewell to Liouvillians (2002)
Oganesyan, Vadim, Chalker, J. T., Sondhi, S. L.
We examine the Liouvillian approach to the quantum Hall plateau transition, as introduced recently by Sinova, Meden, and Girvin [Phys. Rev. B {\bf 62}, 2008 (2000)] and developed by Moore, Sinova and...
Classical dimers on the triangular lattice (2002)
Fendley, P., Moessner, R., Sondhi, S. L.
We study the classical hard-core dimer model on the triangular lattice. Following Kasteleyn's fundamental theorem on planar graphs, this problem is soluble by Pfaffians. This model is particularly...
Resonating valence bond liquid physics on the triangular lattice (2002)
We give an account of the short-range RVB liquid phase on the triangular lattice, starting from an elementary introduction to quantum dimer models including details of the overlap expansion used to...
Gaussian superconducting fluctuations, thermal transport, and the Nernst effect (2002)
Ussishkin, Iddo, Sondhi, S. L., Huse, David A.
We calculate the contribution of superconducting fluctuations to thermal transport in the normal state, for low magnetic fields. We do so in the Gaussian approximation to their critical dynamics...
Spin-Peierls phases in pyrochlore antiferromagnets (2002)
Tchernyshyov, Oleg, Moessner, R., Sondhi, S. L.
In the highly frustrated pyrochlore magnet spins form a lattice of corner sharing tetrahedra. We show that the tetrahedral ``molecule'' at the heart of this structure undergoes a Jahn-Teller...
Liquid-gas and other unusual thermal phase transitions in some large-N magnets (2002)
Tchernyshyov, O., Sondhi, S. L.
Much insight into the low temperature properties of quantum magnets has been gained by generalizing them to symmetry groups of order N, and then studying the large N limit. In this paper we consider...
Order by distortion and string modes in pyrochlore antiferromagnet (2001)
Tchernyshyov, O., Moessner, R., Sondhi, S. L.
We study the effects of magnetoelastic couplings on pyrochlore antiferromagnets. We employ Landau theory, extending an investigation begun by Yamashita and Ueda for the case of S=1, and semiclassical...
Planar pyrochlore, quantum ice and sliding ice (2001)
Moessner, R., Tchernyshyov, Oleg, Sondhi, S. L.
We study quantum antiferromagnetism on the highly frustrated checkerboard lattice, also known as the square lattice with crossings. The quantum Heisenberg antiferromagnet on this lattice is of...
The phase diagram of the hexagonal lattice quantum dimer model (2001)
Moessner, R., Sondhi, S. L., Chandra, P.
We discuss the phase diagram of the quantum dimer model on the hexagonal (honeycomb) lattice. In addition to the columnar and staggered valence bond solids which have been discussed in previous work,...
Short-ranged RVB physics, quantum dimer models and Ising gauge theories (2001)
Moessner, R., Sondhi, S. L., Fradkin, Eduardo
Quantum dimer models are believed to capture the essential physics of antiferromagnetic phases dominated by short-ranged valence bond configurations. We show that these models arise as particular...
Ising models of quantum frustration (2000)
We report on a systematic study of two dimensional, periodic, frustrated Ising models with a quantum dynamics introduced via a transverse magnetic field. The systems studied are the triangular and...
Breakdown of Conformal Invariance at Strongly Random Critical Points (2000)
Hastings, M. B., Sondhi, S. L.
We consider the breakdown of conformal and scale invariance in random systems with strongly random critical points. Extending previous results on one-dimensional systems, we provide an example of a...
An RVB phase in the triangular lattice quantum dimer model (2000)
We study the quantum dimer model on the triangular lattice, which is expected to describe the singlet dynamics of frustrated Heisenberg models in phases where valence bond configurations dominate...
Sliding Phases via Magnetic Fields (2000)
We show that three dimensional "sliding" analogs of the Kosterlitz-Thouless phase, in stacked classical two-dimensional XY models and quantum systems of coupled Luttinger Liquids, can be enlarged by...
Notes on Infinite Layer Quantum Hall Systems (2000)
Naud, J. D., Pryadko, Leonid P., Sondhi, S. L.
We study the fractional quantum Hall effect in three dimensional systems consisting of infinitely many stacked two dimensional electron gases placed in transverse magnetic fields. This limit...
The fractional quantum Hall effect in infinite layer systems (2000)
Naud, J. D., Pryadko, Leonid P., Sondhi, S. L.
Stacked two dimensional electron systems in transverse magnetic fields exhibit three dimensional fractional quantum Hall phases. We analyze the simplest such phases and find novel bulk properties,...
Edge Dynamics in Quantum Hall Bilayers II: Exact Results with Disorder and Parallel Fields (2000)
Naud, J. D., Pryadko, Leonid P., Sondhi, S. L.
We study edge dynamics in the presence of interlayer tunneling, parallel magnetic field, and various types of disorder for two infinite sequences of quantum Hall states in symmetric bilayers. These...
Slow holes in the triangular Ising antiferromagnet (2000)
We consider the problem of the doped Ising antiferromagnet on the frustrated triangular lattice in the limit where the hole kinetic energy is much smaller than the Ising exchange. For a {\it single}...
Disorder from Disorder in a Strongly Frustrated Transverse Field Ising Chain (2000)
Priour Jr, D. J., Gelfand, M. P., Sondhi, S. L.
We study a one-dimensional chain of corner-sharing triangles with antiferromagnetic Ising interactions along its bonds. Classically, this system is highly frustrated with an extensive entropy at T =...
We study the superconducting instability in systems with long but finite ranged, attractive, pairing interactions. We show that such long-ranged superconductors exhibit a new class of fluctuations in...
Two-dimensional periodic frustrated Ising models in a transverse field (1999)
Moessner, R., Sondhi, S. L., Chandra, P.
We investigate the interplay of classical degeneracy and quantum dynamics in a range of periodic frustrated transverse field Ising systems at zero temperature. We find that such dynamics can lead to...
Zeeman and Orbital Effects of an in-Plane Magnetic Field in Cuprate Superconductors (1999)
We discuss the effects of a magnetic field applied parallel to the Cu-O ($ab$) plane of the high $T_c$ cuprate superconductors. After briefly reviewing the Zeeman effect of the field, we study the...
Quantum Hall Bilayers and the Chiral Sine-Gordon Equation (1999)
Naud, J. D., Pryadko, Leonid P., Sondhi, S. L.
The edge state theory of a class of symmetric double-layer quantum Hall systems with interlayer electron tunneling reduces to the sum of a free field theory and a field theory of a chiral Bose field...
Dynamics of the Compact, Ferromagnetic \nu=1 Edge (1999)
Karlhede, A., Lejnell, K., Sondhi, S. L.
We consider the edge dynamics of a compact, fully spin polarized state at filling factor $\nu=1$. We show that there are two sets of collective excitations localized near the edge: the much studied,...
The transverse magnetoresistance of the two-dimensional chiral metal (1998)
We consider the two-dimensional chiral metal, which exists at the surface of a layered, three-dimensional sample exhibiting the integer quantum Hall effect. We calculate its magnetoresistance in...
Effective Action Studies of Quantum Hall Spin Textures (1998)
Lejnell, K., Karlhede, A., Sondhi, S. L.
We report on analytic and numerical studies of spin textures in quantum Hall systems using a long-wavelength effective action for the magnetic degrees of freedom derived previously. The majority of...
Coulomb and Hard Core Skyrmion Tails (1998)
Quantum Hall skyrmions are quantized solitons of a ferromagnetic O(3) sigma-model. The reference, classical, solutions depend upon the interaction between the electrons and exhibit completely...
Response of a $d_{x^2-y^2}$ Superconductor to a Zeeman Magnetic Field (1997)
We study the response of a two dimensional $d_{x^2-y^2}$ superconductor to a magnetic field that couples only to the spins of the electrons. In contrast to the s-wave case, the $d_{x^2-y^2}$ state is...
A New Transport Regime in the Quantum Hall Effect (1997)
Shahar, D., Hilke, M., Li, C. C., Tsui, D. C., Sondhi, S. L., Razeghi, M.
This paper describes an experimental identification and characterization of a new low temperature transport regime near the quantum Hall-to-insulator transition. In this regime, a wide range of...
Quantum Hall Skyrmions with Higher Topological Charge (1997)
Lilliehook, D., Lejnell, K., Karlhede, A., Sondhi, S. L.
We have investigated quantum Hall skyrmions at filling factor \nu=1 carrying more than one unit of topological, and hence electric, charge. Using a combination of analytic and numerical methods we...
Hartree-Fock Theory of Skyrmions in Quantum Hall Ferromagnets (1996)
Fertig, H. A., Brey, L., Cote, R., MacDonald, A. H., Karlhede, A., Sondhi, S. L.
We report on a study of the charged-skyrmion or spin-texture excitations which occur in quantum Hall ferromagnets near odd Landau level filling factors. Particle-hole symmetry is used to relate the...
A different view of the quantum Hall plateau-to-plateau transitions (1996)
Shahar, D., Tsui, D. C., Shayegan, M., Shimshoni, E., Sondhi, S. L.
We demonstrate experimentally that the transitions between adjacent integer quantum Hall (QH) states are equivalent to a QH-to-insulator transition occurring in the top Landau level, in the presence...
Duality Near Quantum Hall Transitions (1996)
Shimshoni, E., Sondhi, S. L., Shahar, D.
A recent experiment by Shahar et al, on the phase transitions between quantum Hall states and the insulator, found that the current-voltage characteristics in the two phases are related by symmetry....
Continuous Quantum Phase Transitions (1996)
Sondhi, S. L., Girvin, S. M., Carini, J. P., Shahar, D.
A quantum system can undergo a continuous phase transition at the absolute zero of temperature as some parameter entering its Hamiltonian is varied. These transitions are particularly interesting...
Two point-contact interferometer for quantum Hall systems (1996)
Chamon, C. De C., Freed, D. E., Kivelson, S. A., Sondhi, S. L., Wen, X. G.
We propose a device, consisting of a Hall bar with two weak barriers, that can be used to study quantum interference effects in a strongly correlated system. We show how the device provides a way of...
The Nature of the Hall Insulator (1996)
Shahar, D., Tsui, D. C., Shayegan, M., Cunningham, J. E., Shimshoni, E., Sondhi, S. L.
We have conducted an experimental study of the linear transport properties of the magnetic-field induced insulating phase which terminates the quantum Hall (QH) series in two dimensional electron...
Textured Edges in Quantum Hall Systems (1996)
Karlhede, A., Kivelson, S. A., Lejnell, K., Sondhi, S. L.
We have investigated the formation of spin textures at the edges of quantum Hall systems for several ferromagnetic filling factors. The textures are driven by the same physics that leads to...
Many skyrmion wave functions and skyrmion statistics in quantum Hall ferromagnets (1996)
We determine the charge and statistical angle of skyrmions in quantum Hall ferromagnets by performing Berry phase calculations based on the microscopic variational wave functions for many-skyrmion...
A Field Theory for the Read Operator (1996)
We introduce a new field theory for studying quantum Hall systems. The quantum field is a modified version of the bosonic operator introduced by Read. In contrast to Read's original work we do {\em...
Evidence for charge-flux duality near the quantum Hall liquid to insulator transition (1995)
Shahar, D., Tsui, D. C., Shayegan, M., Shimshoni, E., Sondhi, S. L.
We examine the longitudinal, non-linear, current-voltage characteristics near the quantum Hall liquid to insulator transition and show that a simple mapping exists between the characteristics on the...
Skyrmions in Higher Landau Levels (1995)
We calculate the energies of quasiparticles with large numbers of reversed spins (``skyrmions'') for odd integer filling factors 2k+1, k is greater than or equals 1. We find, in contrast with the...
Fractional Spin for Quantum Hall Effect Quasiparticles (1994)
Einarsson, T., Sondhi, S. L., Girvin, S. M., Arovas, D. P.
We investigate the issue of whether quasiparticles in the fractional quantum Hall effect possess a fractional intrinsic spin. The presence of such a spin $S$ is suggested by the spin-statistics...
Off-diagonal Interactions, Hund's Rules and Pair-binding in Hubbard Molecules (1994)
Sondhi, S. L., Gelfand, M. P., Lin, H. Q., Campbell, D. K.
We have studied the effect of including nearest-neighbor, electron-electron interactions, in particular the off-diagonal (non density-density) terms, on the spectra of truncated tetrahedral and...
Landau Level Mixing and Solenoidal Terms in Lowest Landau Level Currents (1994)
We calculate the lowest Landau level (LLL) current by working in the full Hilbert space of a two dimensional electron system in a magnetic field and keeping all the non-vanishing terms in the high...
Off-Diagonal Long Range Order and Scaling in a Disordered Quantum Hall System (1994)
We have numerically studied the bosonic off-diagonal long range order, introduced by Read to describe the ordering in ideal quantum Hall states, for noninteracting electrons in random potentials...
The Quantum Hall Effect in Drag: Inter-layer Friction in Strong Magnetic Fields (1993)
Shimshoni, Efrat, Sondhi, S. L.
We study the Coulomb drag between two spatially separated electron systems in a strong magnetic field, one of which exhibits the quantum Hall effect. At a fixed temperature, the drag mimics the...