arXiv subjects

G. Mirarchi

Publications and source records attributed to G. Mirarchi.

3 recordsLinked to original sources

arXiv2026

Anomalous thermopower from the drag of overdamped collective modes

Inspired by the observation of a Seebeck coefficient ratio that exhibits a seemingly logarithmic divergence at low temperature in high-temperature superconducting cuprates, we show that a mechanisms similar to the standard phonon drag can give rise to anomalies in the thermopower of a metal, if the dragged collective mode is overdamped, with a damping coefficient that increases with lowering the temperature. Our finding adds a piece to the puzzle of the strange-metal behavior observed in many different systems and supports our proposal that overdamped charge density fluctuations can be responsible of such a behavior in high-temperature superconducting cuprates.

cond-mat.str-el↗

arXiv2023

Tuning the ground state of cuprate high-critical-temperature superconducting thin films by nanofaceted substrates

Anisotropic transport properties have been assessed in a number of cuprate superconductors, providing evidence for a nematic state. Here, we analyze recent experimental data for ultrathin YBa$_2$Cu$_3$O$_{7-x}$ (YBCO) films, where nematicity is induced via strain engineering, leading to a suppression of charge density wave scattering along the orthorhombic a-axis and a concomitant enhancement of strange metal behavior along the b-axis. It is shown that the anisotropic properties strongly depend on the substrate, which we characterize by atomic force microscopy (AFM). Based on the AFM data, we provide a microscopic model that can account for the absence (presence) of nematicity and the resulting transport properties in films grown on SrTiO$_3$ (MgO) substrates.

cond-mat.supr-con↗

arXiv2020

Dissipation-driven strange metal behavior

Anomalous metallic properties are often observed in the proximity of quantum critical points (QCPs), with violation of the Fermi Liquid paradigm. We propose a scenario where, due to the presence of a nearby QCP, dynamical fluctuations of the order parameter with finite correlation length mediate a nearly isotropic scattering among the quasiparticles over the entire Fermi surface. This scattering produces an anomalous metallic behavior, which is extended to the lowest temperatures by an increase of the damping of the fluctuations. We phenomenologically identify one single parameter ruling this increasing damping when the temperature decreases, accounting for both the linear-in-temperature resistivity and the seemingly divergent specific heat observed, e.g., in high-temperature superconducting cuprates and some heavy-fermion metals.

cond-mat.str-el↗