Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session F49: Strange Metal Transport in Cuprates and Fe-based SuperconductorsInvited Live
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Sponsoring Units: DCMP Chair: Richard Greene, University of Maryland, College Park |
Tuesday, March 16, 2021 11:30AM - 12:06PM Live |
F49.00001: Strange metal Magnetoresistance and Hall effect in BaFe2(As1-xPx)2 Invited Speaker: Nikola Maksimovic Among the most puzzling features of high-temperature superconductors is the behavior of the resistive non-superconducting state, often called a strange metal phase. Recently, the magnetic field-dependence of the resistivity, the magnetoresistance, of these materials has become a topic of intense interest. In particular, a linear-in-field magnetoresistance, and an unusual scaling relation with temperature, have been observed as quite general and puzzling phenomena in strange metals. In this talk, I will discuss a magnetoresistance model based on orbital motion in the presence of the sharply anisotropic Fermi surface and scattering time induced by antiferromagnetic order and fluctuations. I will present new experimental data demonstrating the validity of this model both in the antiferromagnetically ordered and strange metal phases of P-substituted BaFe2As2. Finally, I will discuss the potential applicability of these models to a variety of high-temperature superconducting materials, and possible extensions to the off-diagonal component of the magnetoresistance tensor (the hall resistivity), which often exhibits anomalous behavior in these materials as well. |
Tuesday, March 16, 2021 12:06PM - 12:42PM Live |
F49.00002: Scale-invariant magnetoresistance in a cuprate superconductor Invited Speaker: Paula Giraldo-Gallo The anomalous metallic state in the high-temperature superconducting cuprates is masked by superconductivity near a quantum critical point. Applying high magnetic fields to suppress superconductivity has enabled detailed studies of the normal state, yet the direct effect of strong magnetic fields on the metallic state is poorly understood. In this talk, we present measurements of high-field magnetoresistance of thin-film La2-xSrxCuO4 cuprate in the vicinity of the critical doping, 0.161 ≤ p ≤ 0.190. We find that the metallic state exposed by suppressing superconductivity is characterized by magnetoresistance that is linear in magnetic fields up to 80 Tesla. The magnitude of the linear-in-field resistivity mirrors the magnitude and doping evolution of the well-known linear-in-temperature resistivity that has been associated with quantum criticality in high-temperature superconductors. |
Tuesday, March 16, 2021 12:42PM - 1:18PM Live |
F49.00003: Strange metal transport in electron-doped La2-xCexCuO4 Invited Speaker: Tarapada Sarkar I report measurements of normal state resistivity, Hall Effect, magnetoresistance, and thermopower in the electron-doped cuprate La2-xCexCuO4 for 0.19≥ x ≥0.08 as a function of temperature. The surprising results are: |
Tuesday, March 16, 2021 1:18PM - 1:54PM Live |
F49.00004: Evidence for two charge sectors in the strange metal phase of overdoped cuprates Invited Speaker: Nigel Hussey In this presentation, I describe my group’s recent exploration of the low-temperature (T < 50 K) magnetotransport in two families of single-layer cuprates - Tl2201 and La-Bi2201 - across the so-called strange metal regime. Firstly, we report a study of the Hall number nH(0) in the low T, high field limit that within conventional transport theory, is simply related to the number of charge carriers. We find that the hole concentration inferred from nH(0) increases smoothly from p to 1 + p, where p is the number of holes doped into the parent insulating state, over a wide range of doping beyond the critical hole doping at which the pseudogap in the single-particle response closes. We also report the observation of quadrature scaling in the magnetoresistance - believed to be associated with Planckian dissipation - as well as other signatures of incoherent transport. From analysis of the Hall and magnetoresistance, we conclude that there are in fact two charge sectors in the strange metal phase of overdoped cuprates, one containing coherent quasiparticles, the other incoherent `Planckian' dissipators. |
Tuesday, March 16, 2021 1:54PM - 2:30PM Live |
F49.00005: Thermal diffusivity above the Mott-Ioffe-Regel limit Invited Speaker: Aharon Kapitulnik We present high-resolution thermal diffusivity measurements on several near optimally doped electron- and hole-doped cuprate systems in a temperature range that passes through the Mott-Ioffe-Regel limit, above which the quasiparticle picture fails. Our primary observations are that the inverse thermal diffusivity is linear in temperature and can be fitted to DQ-1=aT+b. The slope a is interpreted through the Planckian relaxation time τ≈h/kBT and a thermal diffusion velocity vB, which is close, but larger than the sound velocity. The intercept b≈h/m represent a crossover (quantum) diffusion constant that separates coherent from incoherent quasiparticles. These observations suggest that both phonons and electrons participate in the thermal transport and both reach the Planckian limit for relaxation time. Where itinerant electrons are absent, a similar behavior is obtained for the insulating phases where the constant b is absent. |
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