Aavishkar A. Patel
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View article: Strange Metals and Planckian Transport in a Gapless Phase from Spatially Random Interactions
Strange Metals and Planckian Transport in a Gapless Phase from Spatially Random Interactions Open
“Strange” metals that do not follow the predictions of Fermi liquid theory are prevalent in materials that feature superconductivity arising from electron interactions. In recent years, it has been hypothesized that spatial randomness in e…
View article: Fractionalized Fermi liquids and the cuprate phase diagram
Fractionalized Fermi liquids and the cuprate phase diagram Open
We review a theoretical framework for the cuprate superconductors, rooted in a fractionalized Fermi liquid (FL*) description of the intermediate-temperature pseudogap phase at low doping. The FL* theory predicted hole pockets each of fract…
View article: Thermopower across Fermi-volume-changing quantum phase transitions without translational symmetry breaking
Thermopower across Fermi-volume-changing quantum phase transitions without translational symmetry breaking Open
We describe the evolution of low-temperature thermopower across Fermi-volume-changing quantum phase transitions in Kondo lattice models without translational symmetry breaking. This transition moves from a heavy Fermi liquid with a convent…
View article: Enhanced Strange Metallicity due to Hubbard-U Coulomb Repulsion
Enhanced Strange Metallicity due to Hubbard-U Coulomb Repulsion Open
We solve a model of electrons with Hubbard-$U$ Coulomb repulsion and a random Yukawa coupling to a two-dimensional bosonic bath, using an extended dynamical mean field theory scheme. Our model exhibits a quantum critical point, at which th…
View article: Strange metal and superconductor in the two-dimensional Yukawa-Sachdev-Ye-Kitaev model
Strange metal and superconductor in the two-dimensional Yukawa-Sachdev-Ye-Kitaev model Open
The two-dimensional Yukawa-Sachdev-Ye-Kitaev (2d-YSYK) model provides a universal theory of quantum phase transitions in metals in the presence of quenched random spatial fluctuations in the local position of the quantum critical point. It…
View article: Localization of overdamped bosonic modes and transport in strange metals
Localization of overdamped bosonic modes and transport in strange metals Open
The strange metal phase of correlated electrons materials was described in a recent theory by a model of a Fermi surface coupled a two-dimensional quantum critical bosonic field with a spatially random Yukawa coupling. With the assumption …
View article: Localization of overdamped bosonic modes and transport in strange metals
Localization of overdamped bosonic modes and transport in strange metals Open
A recent theory described strange metal behavior in a model of a Fermi surface coupled a two-dimensional quantum critical bosonic field with a spatially random Yukawa coupling. With the assumption of self-averaging randomness, similar to t…
View article: Theory of shot noise in strange metals
Theory of shot noise in strange metals Open
We extend the theory of shot noise in coherent metals to shot noise in strange metals without quasiparticle excitations. This requires a generalization of the Boltzmann equation with a noise source to distribution functions which depend in…
View article: Cyclotron resonance and quantum oscillations of critical Fermi surfaces
Cyclotron resonance and quantum oscillations of critical Fermi surfaces Open
Kohn's theorem places strong constraints on the cyclotron response of Fermi liquids. Recent observations of a doping dependence in the cyclotron mass of La$_{2-x}$Sr$_x$CuO$_4$ (Legros et al., Phys. Rev. B 106, 195110 (2022)) are therefore…
View article: Theory of shot noise in strange metals
Theory of shot noise in strange metals Open
We extend the theory of shot noise in coherent metals to shot noise in strange metals without quasiparticle excitations. This requires a generalization of the Boltzmann equation with a noise source to distribution functions which depend in…
View article: Pair Density Wave Order from Electron Repulsion
Pair Density Wave Order from Electron Repulsion Open
A pair density wave (PDW) is a superconductor whose order parameter is a periodic function of space, without an accompanying spatially uniform component. Since PDWs are not the outcome of a weak-coupling instability of a Fermi liquid, a ge…
View article: Pair density wave order from electron repulsion
Pair density wave order from electron repulsion Open
A pair density wave (PDW) is a superconductor whose order parameter is a periodic function of space, without an accompanying spatially-uniform component. Since PDWs are not the outcome of a weak-coupling instability of a Fermi liquid, a ge…
View article: Maximal Quantum Chaos of the Critical Fermi Surface
Maximal Quantum Chaos of the Critical Fermi Surface Open
We investigate the many-body quantum chaos of non-Fermi liquid states with Fermi surfaces in two spatial dimensions by computing their out-of-time-order correlation functions. Using a recently proposed large $N$ theory for the critical Fer…
View article: Large $N$ theory of critical Fermi surfaces II: conductivity
Large $N$ theory of critical Fermi surfaces II: conductivity Open
A Fermi surface coupled to a scalar field can be described in a $1/N$ expansion by choosing the fermion-scalar Yukawa coupling to be random in the $N$-dimensional flavor space, but invariant under translations. We compute the conductivity …
View article: Solvable theory of a strange metal at the breakdown of a heavy Fermi liquid
Solvable theory of a strange metal at the breakdown of a heavy Fermi liquid Open
We introduce an effective theory for quantum critical points (QCPs) in heavy fermion systems, involving a change in carrier density without symmetry breaking. Our new theory captures a strongly coupled metallic QCP, leading to robust margi…
View article: Many-body energy invariant for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>T</mml:mi></mml:math>-linear resistivity
Many-body energy invariant for -linear resistivity Open
The description of dynamics of strongly correlated quantum matter is a\nchallenge, particularly in physical situations where a quasiparticle\ndescription is absent. In such situations, however, the many-body Kubo formula\nfrom linear respo…
View article: Universal theory of strange metals from spatially random interactions
Universal theory of strange metals from spatially random interactions Open
We consider two-dimensional metals of fermions coupled to quantum critical scalars, the latter representing order parameters or emergent gauge fields. We show that at low temperatures ($T$), such metals generically exhibit strange metal be…
View article: A better large N limit of the electron-boson problem?
A better large N limit of the electron-boson problem? Open
The electron-boson problem -i.e. the problem of a dense electron fluid interacting via a Yukawa coupling with a bosonic field which could represent phonons or the collective fluctuations of an order parameter near a quantum critical point …
View article: Solvable Theory of a Strange Metal at the Breakdown of a Heavy Fermi\n Liquid
Solvable Theory of a Strange Metal at the Breakdown of a Heavy Fermi\n Liquid Open
We introduce an effective theory for quantum critical points (QCPs) in heavy\nfermion systems, involving a change in carrier density without symmetry\nbreaking. Our new theory captures a strongly coupled metallic QCP, leading to\nrobust ma…
View article: Slope invariant <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>T</mml:mi></mml:math>-linear resistivity from local self-energy
Slope invariant -linear resistivity from local self-energy Open
A theoretical understanding of the enigmatic linear-in-temperature (T) resistivity, ubiquitous in strongly correlated metallic systems, has been a long sought-after goal. Furthermore, the slope of this robust T-linear resistivity is also o…
View article: Thermoelectric power of Sachdev-Ye-Kitaev islands: Probing Bekenstein-Hawking entropy in quantum matter experiments
Thermoelectric power of Sachdev-Ye-Kitaev islands: Probing Bekenstein-Hawking entropy in quantum matter experiments Open
The Sachdev-Ye-Kitaev (SYK) model describes electrons with random and all-to-all interactions and realizes a many-body state without quasiparticle excitations and a nonvanishing extensive entropy $S_0$ in the zero-temperature limit. Its lo…
View article: Many-body chaos in the antiferromagnetic quantum critical metal
Many-body chaos in the antiferromagnetic quantum critical metal Open
Here, we compute the scrambling rate at the antiferromagnetic (AFM) quantum critical point, using the fixed point theory found by Schlief, Lunts, and Lee. At this strongly coupled fixed point, there is an emergent control parameter $w \\ll…
View article: Theory of a Planckian Metal
Theory of a Planckian Metal Open
We present a lattice model of fermions with N flavors and random interactions that describes a Planckian metal at low temperatures T→0 in the solvable limit of large N. We begin with quasiparticles around a Fermi surface with effective mas…
View article: Many-body chaos in the antiferromagnetic quantum critical metal
Many-body chaos in the antiferromagnetic quantum critical metal Open
We compute the scrambling rate at the antiferromagnetic (AFM) quantum critical point, using the fixed point theory of Phys. Rev. X $\boldsymbol{7}$, 021010 (2017). At this strongly coupled fixed point, there is an emergent control paramete…
View article: Transport, criticality, and chaos in fermionic quantum matter at nonzero density
Transport, criticality, and chaos in fermionic quantum matter at nonzero density Open
This dissertation is a study of various aspects of metals with strong interactions between electrons, with a particular emphasis on the problem of charge transport through them. We consider the physics of clean or weakly-disordered metals …
View article: Coherent Superconductivity with a Large Gap Ratio from Incoherent Metals
Coherent Superconductivity with a Large Gap Ratio from Incoherent Metals Open
A mysterious incoherent metallic (IM) normal state with T-linear resistivity is ubiquitous among strongly correlated superconductors. Recent progress with microscopic models exhibiting IM transport has presented the opportunity for us to s…
View article: Critical strange metal from fluctuating gauge fields in a solvable random model
Critical strange metal from fluctuating gauge fields in a solvable random model Open
Building upon techniques employed in the construction of the Sachdev-Ye-Kitaev (SYK) model, which is a solvable $0+1$ dimensional model of a non-Fermi liquid, we develop a solvable, infinite-ranged random-hopping model of fermions coupled …
View article: A critical strange metal from fluctuating gauge fields in a solvable random model
A critical strange metal from fluctuating gauge fields in a solvable random model Open
Building upon techniques employed in the construction of the Sachdev-Ye-Kitaev (SYK) model, which is a solvable $0+1$ dimensional model of a non-Fermi liquid, we develop a solvable, infinite-ranged random-hopping model of fermions coupled …
View article: Magnetotransport in a model of a disordered strange metal
Magnetotransport in a model of a disordered strange metal Open
Despite much theoretical effort, there is no complete theory of the 'strange' metal state of the high temperature superconductors, and its linear-in-temperature, $T$, resistivity. Recent experiments showing an unexpected linear-in-field, $…
View article: Hydrodynamic flows of non-Fermi liquids: Magnetotransport and bilayer drag
Hydrodynamic flows of non-Fermi liquids: Magnetotransport and bilayer drag Open
We consider a hydrodynamic description of transport for generic two\ndimensional electron systems that lack Galilean invariance and do not fall into\nthe category of Fermi liquids. We study magnetoresistance and show that it is\ngoverned o…