Bulletin of the American Physical Society
APS March Meeting 2024
Monday–Friday, March 4–8, 2024; Minneapolis & Virtual
Session B07: Non-Fermi Liquid Transport |
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Sponsoring Units: DCMP Chair: Elio König, Max-Planck-Institute for Solid State Research Room: L100H |
Monday, March 4, 2024 11:30AM - 11:42AM |
B07.00001: Noise Measurements in Thin-film Strange Metal Sr3Ru2O7 Nanowires Dale T Lowder, Douglas Natelson, Liyang Chen, Jihwan Jeong, Jinkwon Kim, Tae Won Noh Sr3Ru2O7 (SRO327) is a material with a strange metal phase extending from a magnetic quantum critical point at Hc~7.8T. Noise measurements of SRO327 nanowires will allow direct comparison of the noise response in regimes of strange metallicity and normal metallicity within the same material. These noise measurements seek to probe the electron-phonon coupling and electron-electron interactions via Johnson-Nyquist noise and shot noise respectively. SRO327’s unique capability to tune in and out of the strange metal phase with magnetic field will allow direct comparison to measurements taken in the normal metal phase. Initial results will be presented, as well as estimates of the electron-phonon energy relaxation rate in this material. |
Monday, March 4, 2024 11:42AM - 11:54AM |
B07.00002: Shot Noise in Correlated Electron Systems Yiming Wang, Chandan Setty, Shouvik Sur, Liyang Chen, Silke Paschen, Douglas Natelson, Qimiao Si Shot noise, an intrinsic representation of fluctuations in electric current, serves as a significant probe into the realm of strong correlations within quantum materials [1]. Traditionally utilized in discerning the elementary charge borne by quasiparticles, shot noise provides critical insights into the microscopic properties of quantum systems. In this study [2], we focuses on the analysis of quantum shot noise within a correlated diffusive metal, achieved by formulating a Boltzmann transport equation optimized for correlated regimes. We examine the impact of electron correlations on the Fano factor — the proportion of current noise to DC current. We discuss the relevance of our results to recent shot noise experiments in the strange-metal regime of a quantum critical heavy fermion metal YbRh2Si2 [3]. |
Monday, March 4, 2024 11:54AM - 12:06PM |
B07.00003: Theory of shot noise in strange metals Alexander Nikolaenko, Subir Sachdev, Aavishkar A Patel
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Monday, March 4, 2024 12:06PM - 12:18PM |
B07.00004: Low Energy Charge Fluctuations in a Strange Metal Xuefei Guo, Jin Chen, Farzaneh Hoveyda, Simon L Bettler, Dipanjan Chaudhuri, Caitlin S Kengle, John A Schneeloch, Ruidan Zhong, Genda Gu, Philip W Phillips, Tai-Chang Chiang, Peter Abbamonte The strange metal phase with T-linear resistivity is believed to be related to Planckian dissipation. Our recent experiments using momentum-resolved EELS (M-EELS), from the strange metal Bi2.1Sr1.9CaCu2O8+x (Bi-2212), show that at q < 0.04 r.l.u., the spectra have a well-defined plasmon consistent with IR optics. At q > 0.04 r.l.u., the M-EELS data behave like a featureless continuum [1-3]. Here, using improved resolution, we report the new, finite-q measurements of the charge susceptibility on Bi-2212 at low energy, where ω ~ kBT. The spectra show ω/T-scaling with a power law exponent α ~ -0.92. Above Tc, the M-EELS spectra could be fit well by a CFT0+1 theory with conformal dimension δ ~ 0.06, which significantly deviates from the Marginal Fermi Liquid form (δ = 0.5). The M-EELS spectra can also be described in terms of relaxational dynamics where the charge dynamics exhibits Planckian dissipation. |
Monday, March 4, 2024 12:18PM - 12:30PM |
B07.00005: Bound on thermalization from hydrodynamic fluctuations Luca V Delacretaz Strange metal phenomenology has motivated the "Planckian bound", a conjecture that there is a universal quantum statistical mechanics limit on a suitable local equilibration time. However, it has been debated how to define this equilibration time, given that natural candidates (such as transport time or quasiparticle lifetime) seem to allow for violations of the conjectured bound. I will propose a sharp and universal definition of local equilibration time in local many-body systems as the time scale of emergence of diffusion. This definition does not rely on an underlying Boltzmann description, and applies equally well to spin chains, insulators, metals, fluids, I will then show that this time scale is bounded by the strong coupling scale of the effective field theory of diffusion. For a class of systems, this leads to the Planckian bound. |
Monday, March 4, 2024 12:30PM - 12:42PM |
B07.00006: Strong disorder effects in the theory of strange metals Subir Sachdev, Aavishkar A Patel A recent theory has described strange metal behavior in a model of a Fermi surface coupled a two-dimensional quantum-critical scalar field with a spatially random Yukawa coupling. With the assumption of self-averaging randomness, similar to that in the Sachdev-Ye-Kitaev model, numerous observed properties of a strange metal were obtained, including the linear-in-temperature resistivity. The Harris criterion implies that the self-averaging of randomness must fail at low enough temperatures near the quantum critical point. We examine the spectrum of the scalar propagator in each random realization, assuming Landau-damping from the fermions, a spatially random mass, and a continuous flavor symmetry. We find behavior consistent with emergence of the physics of the random transverse-field Ising model, as has been proposed earlier by Hoyos, Kotabage, and Vojta. This emergent low temperature regime also has resistivity which is (nearly) linear-in-temperature, and extends into a "foot" away from the quantum-critical fan, as observed in several cuprates. |
Monday, March 4, 2024 12:42PM - 12:54PM |
B07.00007: Genesis of pseudogaps from electron-lattice resonances Anton M Graf, Joonas Keski-Rahkonen, Alhun Aydin, Eric J Heller Pseudogaps, often associated with unconventional superconductors, have long posed a challenge to condensed matter theory. Here, we discuss a possible solution to the pseudogap problem by invoking the recently developed picture of quantum acoustics, which has already succeeded in explaining some of the strange metal mysteries, such as T-linear resistivity and the displaced Drude peak. We describe lattice vibrations within the coherent state formalism, akin to Glauber states in quantum optics, which naturally suggests radically different approximations compared to Fock states, and leads to a non-perturbative treatment of the charge carriers in a dynamical deformation potential field. We find that in some materials, particularly low-(electron-)doped cuprates, acoustic and carrier bands can intersect in a range of important energies and momenta. At these junctures, a resonant coupling between carriers and the lattice takes place, destroying the underlying Fermi surfaces. This strong coupling induces the formation of gaps and can give rise to the emergence of hybrid carrier-phonon quasiparticles. Crucially, a (quantum-acoustical) pseudogap materializes when such a gapped region lies in the vicinity of the Fermi level. The patterns of these pseudogaps align with the existing ARPES data, offering a simple but appealing explanation for their emergence, grounded purely on conventional acoustic and electronic band structures. |
Monday, March 4, 2024 12:54PM - 1:06PM |
B07.00008: Entropy and de Haas-van Alphen oscillations of a three-dimensional marginal Fermi liquid Pavel Nosov, Yi-Ming Wu, Srinivas Raghu We study quantum oscillations (de Haas-van Alphen effect) in a three-dimensional metal tuned to a quantum critical point. The conventional approach to this problem involves extensions of the Lifshitz-Kosevich formula, which breaks down when the correlation length exceeds the cyclotron radius, mainly due to (i) non-analytic finite-temperature dependence of the self-energy, (ii) an enhancement of the oscillatory part of the self-energy by quantum fluctuations, and (iii) non-trivial dynamical scaling laws associated with quantum criticality. By incorporating these effects, we derive the modified oscillation amplitudes of the specific heat and magnetization. Our results manifestly satisfy the third law of thermodynamics (Nernst's theorem) and remain valid in the non-Fermi liquid regime. |
Monday, March 4, 2024 1:06PM - 1:18PM |
B07.00009: Non-linear responses of strange metals Serhii Kryhin, Pavel A Volkov, Subir Sachdev
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Monday, March 4, 2024 1:18PM - 1:30PM |
B07.00010: Non-linear edge dynamics of the Laughlin state Gustavo M Machado Monteiro, Sriram Ganeshan In this presentation, we will explore the non-linear edge dynamics of the Laughlin states. These dynamics are derived from the Chern-Simons-Ginzburg-Landau theory with appropriate boundary conditions, which are compatible with the gauge-anomaly dynamics at the edge of the sample. By employing a systematic perturbation scheme based on scaling analysis, we have assigned dispersive and non-linear terms in the fluid dynamic equations of the Laughlin state at the same perturbation order. As a result, we have derived the Korteweg-de-Vries equation as the weakly non-linear dynamics of the edge states, along with the boundary Hamiltonian of the system. Hence, this work extends the conventional Chiral Luttinger Liquid theory for the edge of the Fractional Quantum Hall (FQH) system by incorporating systematic higher-gradient and non-linear corrections. |
Monday, March 4, 2024 1:30PM - 1:42PM |
B07.00011: Linear resistivity in 2D doped silicon Jeffrey A Ivie, Christopher R Allemang, Deanna M Campbell, Thomas R Sheridan, Steve M Young, Tzu-Ming Lu, Shashank Misra Linear temperature dependence of the resistivity of a variety of materials (strange metals or high carrier density metals) has previously been characterized using the concept of a Planckian bound, where the timescale for inelastic scattering from any source obeys τ > τPl = kBT/ħ. Semiconductor materials, with a wide range of tunable parameters, represent ideal systems for testing concepts related to the Planckian bound but have been limited to 2D quantum well systems (e.g. GaAs), which are generally in the clean and low density limits. Here, we examine the temperature-dependent resistivity of a 2D sheet of highly doped silicon, representing the high disorder & high carrier density limits. We find the resistivity of the material to increase linearly up to 300K. We discuss this result in context of the Planckian bound. |
Monday, March 4, 2024 1:42PM - 1:54PM |
B07.00012: Dissipation Spectrum and Angular Dynamics of 2+1D Non-Fermi Liquids Haoyu Guo The linear-response coefficients of a non-Fermi liquid are encoded in the Bethe-Salpeter kernel. In this work, we study the eigenvalues of the kernel using the Migdal-Eliashberg formalism or the Yukawa-SYK model in the context of a Fermi surface coupled to the Ising-nematic quantum critical point. We find that the generic eigenvalues scale in the same way as the self-energy. For a circular Fermi surface, there are two soft-modes related to the conserved density and momentum of the fermions. The density mode shows a regular diffusion on the Fermi surface, and the momentum mode shows an anomalous angular diffusion dynamics whose diffusion operator contains sixth order derivative. The implications of our formalism include an incoherent quantum critical conductivity and a non-Fermi liquid analog of the tomographic transport regime. |
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