The Experts below are selected from a list of 63744 Experts worldwide ranked by ideXlab platform
Subir Sachdev - One of the best experts on this subject based on the ideXlab platform.
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Fermi Surface reconstruction without symmetry breaking
Physical Review X, 2020Co-Authors: Snir Gazit, Fakher F Assaad, Subir SachdevAbstract:A new model shows how electron fractionalization can mediate a change in a material's Fermi Surface without breaking translational symmetry, thus shedding light on recent puzzling experimental observations.
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Fermi Surface reconstruction without symmetry breaking
arXiv: Strongly Correlated Electrons, 2019Co-Authors: Snir Gazit, Fakher F Assaad, Subir SachdevAbstract:We present a sign-problem free quantum Monte Carlo study of a model, which exhibits quantum phase transitions without symmetry breaking, along with associated changes in the size of the Fermi Surface. The model is an Ising gauge theory on the square lattice coupled to an Ising matter field and spinful `orthogonal' Fermions at half-filling, both carrying Ising gauge charges. In contrast to previous studies, our model hosts an electron-like, gauge-neutral Fermion excitation providing access to Fermi liquid phases. One of the phases of the model is a previously studied orthogonal semi-metal, which has $\mathbb{Z}_2$ topological order, and Luttinger-volume violating Fermi points with gapless orthogonal Fermion excitations. We elucidate the global phase diagram of the model, which also contains a confining Fermi liquid, with a large Luttinger-volume Fermi Surface. We present results for the electron spectral function, showing its evolution from the orthogonal semi-metal with spectral weight near momenta $\{\pm \pi/2, \pm \pi/2\}$, to a large Fermi Surface.
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quantum chaos on a critical Fermi Surface
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Aavishkar A Patel, Subir SachdevAbstract:We compute parameters characterizing many-body quantum chaos for a critical Fermi Surface without quasiparticle excitations. We examine a theory of N species of Fermions at nonzero density coupled to a U ( 1 ) gauge field in two spatial dimensions and determine the Lyapunov rate and the butterfly velocity in an extended random-phase approximation. The thermal diffusivity is found to be universally related to these chaos parameters; i.e., the relationship is independent of N , the gauge-coupling constant, the Fermi velocity, the Fermi Surface curvature, and high-energy details.
Andrew Lucas - One of the best experts on this subject based on the ideXlab platform.
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Electron hydrodynamics with a polygonal Fermi Surface
Physical Review B, 2019Co-Authors: Caleb Q. Cook, Andrew LucasAbstract:Recent experiments have observed hints of hydrodynamic electron flow in a number of materials, not all of which have an isotropic Fermi Surface. We revisit these experiments in $\mathrm{PdCoO}_2$, a quasi-two-dimensional material whose Fermi Surface is a rounded hexagon, and observe that the data appears quantitatively consistent with a non-hydrodynamic interpretation. Nevertheless, motivated by such experiments, we develop a simple model for the low temperature kinetics and hydrodynamics of a two-dimensional Fermi liquid with a polygonal Fermi Surface. A geometric effect leads to a finite number of additional long-lived quasihydrodynamic "imbalance" modes and corresponding qualitative changes in transport at the ballistic-to-hydrodynamic crossover. In the hydrodynamic limit, we find incoherent diffusion and a new dissipative component of the viscosity tensor arising from the explicit breaking of rotational invariance by the Fermi Surface. Finally, we compute the conductance of narrow channels across the ballistic-to-hydrodynamic crossover and demonstrate a modification of the Gurzhi effect that allows for non-monotonic temperature and width dependence in the channel conductance.
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electron hydrodynamics with a polygonal Fermi Surface
Physical Review B, 2019Co-Authors: Caleb Q. Cook, Andrew LucasAbstract:The authors identify a geometric effect that constrains scattering on polygonal Fermi Surfaces and leads to an intermediate transport regime that alters traditional signatures of the ballistic-to-hydrodynamic crossover, including a modification of the well-known Gurzhi effect. In the hydrodynamic limit, the authors find a new dissipative ``rotational viscosity'', which arises from anisotropy in the Fermi Surface and opposes rotations of the electronic fluid. Finally, the authors revisit the putative hydrodynamic transport data in PdCoO${}_{2}$, an ultrapure metal with an approximately hexagonal Fermi Surface.
Joseph J Betouras - One of the best experts on this subject based on the ideXlab platform.
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multicritical Fermi Surface topological transitions
Physical Review Letters, 2019Co-Authors: D V Efremov, Alex Shtyk, Andreas W Rost, Claudio Chamon, A P Mackenzie, Joseph J BetourasAbstract:A wide variety of complex phases in quantum materials are driven by electron-electron interactions, which are enhanced through density of states peaks. A well-known example occurs at van Hove singularities where the Fermi Surface undergoes a topological transition. Here we show that higher order singularities, where multiple disconnected leaves of Fermi Surface touch all at once, naturally occur at points of high symmetry in the Brillouin zone. Such multicritical singularities can lead to stronger divergences in the density of states than canonical van Hove singularities, and critically boost the formation of complex quantum phases via interactions. As a concrete example of the power of these Fermi Surface topological transitions, we demonstrate how they can be used in the analysis of experimental data on ${\mathrm{Sr}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$. Understanding the related mechanisms opens up new avenues in material design of complex quantum phases.
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multicritical Fermi Surface topological transitions
arXiv: Strongly Correlated Electrons, 2018Co-Authors: D V Efremov, Alex Shtyk, Andreas W Rost, Claudio Chamon, A P Mackenzie, Joseph J BetourasAbstract:A wide variety of complex phases in quantum materials are driven by electron-electron interactions, which are magnified by regions in momentum space where the density of states is enhanced. A well known example occurs at van Hove singularities where the Fermi Surface undergoes a topological transition. Here we show that higher order singularities, where multiple disconnected leafs of Fermi Surface touch all at once, naturally occur at points of high symmetry in the Brillouin zone. Such multicritical singularities can lead to stronger divergences in the density of states than canonical van Hove singularities, and further boost the formation of complex quantum phases via interactions. As a concrete example, we demonstrate these theoretical ideas in the analysis of experimental data on Sr$_3$Ru$_2$O$_7$ in the vicinity of the metamagnetic quantum critical point, resolving several previously puzzling aspects of the data.
A P Mackenzie - One of the best experts on this subject based on the ideXlab platform.
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multicritical Fermi Surface topological transitions
Physical Review Letters, 2019Co-Authors: D V Efremov, Alex Shtyk, Andreas W Rost, Claudio Chamon, A P Mackenzie, Joseph J BetourasAbstract:A wide variety of complex phases in quantum materials are driven by electron-electron interactions, which are enhanced through density of states peaks. A well-known example occurs at van Hove singularities where the Fermi Surface undergoes a topological transition. Here we show that higher order singularities, where multiple disconnected leaves of Fermi Surface touch all at once, naturally occur at points of high symmetry in the Brillouin zone. Such multicritical singularities can lead to stronger divergences in the density of states than canonical van Hove singularities, and critically boost the formation of complex quantum phases via interactions. As a concrete example of the power of these Fermi Surface topological transitions, we demonstrate how they can be used in the analysis of experimental data on ${\mathrm{Sr}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$. Understanding the related mechanisms opens up new avenues in material design of complex quantum phases.
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multicritical Fermi Surface topological transitions
arXiv: Strongly Correlated Electrons, 2018Co-Authors: D V Efremov, Alex Shtyk, Andreas W Rost, Claudio Chamon, A P Mackenzie, Joseph J BetourasAbstract:A wide variety of complex phases in quantum materials are driven by electron-electron interactions, which are magnified by regions in momentum space where the density of states is enhanced. A well known example occurs at van Hove singularities where the Fermi Surface undergoes a topological transition. Here we show that higher order singularities, where multiple disconnected leafs of Fermi Surface touch all at once, naturally occur at points of high symmetry in the Brillouin zone. Such multicritical singularities can lead to stronger divergences in the density of states than canonical van Hove singularities, and further boost the formation of complex quantum phases via interactions. As a concrete example, we demonstrate these theoretical ideas in the analysis of experimental data on Sr$_3$Ru$_2$O$_7$ in the vicinity of the metamagnetic quantum critical point, resolving several previously puzzling aspects of the data.
Andreas W Rost - One of the best experts on this subject based on the ideXlab platform.
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multicritical Fermi Surface topological transitions
Physical Review Letters, 2019Co-Authors: D V Efremov, Alex Shtyk, Andreas W Rost, Claudio Chamon, A P Mackenzie, Joseph J BetourasAbstract:A wide variety of complex phases in quantum materials are driven by electron-electron interactions, which are enhanced through density of states peaks. A well-known example occurs at van Hove singularities where the Fermi Surface undergoes a topological transition. Here we show that higher order singularities, where multiple disconnected leaves of Fermi Surface touch all at once, naturally occur at points of high symmetry in the Brillouin zone. Such multicritical singularities can lead to stronger divergences in the density of states than canonical van Hove singularities, and critically boost the formation of complex quantum phases via interactions. As a concrete example of the power of these Fermi Surface topological transitions, we demonstrate how they can be used in the analysis of experimental data on ${\mathrm{Sr}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$. Understanding the related mechanisms opens up new avenues in material design of complex quantum phases.
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multicritical Fermi Surface topological transitions
arXiv: Strongly Correlated Electrons, 2018Co-Authors: D V Efremov, Alex Shtyk, Andreas W Rost, Claudio Chamon, A P Mackenzie, Joseph J BetourasAbstract:A wide variety of complex phases in quantum materials are driven by electron-electron interactions, which are magnified by regions in momentum space where the density of states is enhanced. A well known example occurs at van Hove singularities where the Fermi Surface undergoes a topological transition. Here we show that higher order singularities, where multiple disconnected leafs of Fermi Surface touch all at once, naturally occur at points of high symmetry in the Brillouin zone. Such multicritical singularities can lead to stronger divergences in the density of states than canonical van Hove singularities, and further boost the formation of complex quantum phases via interactions. As a concrete example, we demonstrate these theoretical ideas in the analysis of experimental data on Sr$_3$Ru$_2$O$_7$ in the vicinity of the metamagnetic quantum critical point, resolving several previously puzzling aspects of the data.