Anomalous frequency and temperature dependent scattering in the dilute metallic phase in lightly doped-SrTiO$_3$

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Hauptverfasser: Kumar, K. Santhosh, Lee, Dooyong, Varshney, Shivasheesh, Jalan, Bharat, Armitage, N. P.
Format: Preprint
Veröffentlicht: 2024
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author Kumar, K. Santhosh
Lee, Dooyong
Varshney, Shivasheesh
Jalan, Bharat
Armitage, N. P.
author_facet Kumar, K. Santhosh
Lee, Dooyong
Varshney, Shivasheesh
Jalan, Bharat
Armitage, N. P.
contents The mechanism of superconductivity in materials with aborted ferroelectricity and the emergence of a dilute metallic phase in systems like doped-SrTiO$_3$ are outstanding issues in condensed matter physics. This dilute metal has features both similar and different to those found in the normal state of other unconventional superconductors. We have investigated the optical properties of the dilute metallic phase in doped-SrTiO$_3$ using THz time-domain spectroscopy. At low frequencies the THz response exhibits a Drude-like form as expected for typical metal-like conductivity. We observed the frequency and temperature dependencies to the low energy scattering rate $Γ(ω, T) \propto (\hbarω)^2 + (p πk_BT)^2 $ expected in a conventional Fermi liquid, despite the fact that densities are too small to allow current decay through electron-electron scattering. However we find the lowest known $p$ values of 0.39-0.72. As $p$ is 2 in a canonical Fermi liquid and existing models based on energy dependent elastic scattering bound $p$ from below to 1, our observation lies outside current explanation. Our data also gives insight into the high temperature regime and shows that the temperature dependence of the resistivity derives in part from strong T dependent mass renormalizations.
format Preprint
id arxiv_https___arxiv_org_abs_2402_18767
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Anomalous frequency and temperature dependent scattering in the dilute metallic phase in lightly doped-SrTiO$_3$
Kumar, K. Santhosh
Lee, Dooyong
Varshney, Shivasheesh
Jalan, Bharat
Armitage, N. P.
Strongly Correlated Electrons
Superconductivity
The mechanism of superconductivity in materials with aborted ferroelectricity and the emergence of a dilute metallic phase in systems like doped-SrTiO$_3$ are outstanding issues in condensed matter physics. This dilute metal has features both similar and different to those found in the normal state of other unconventional superconductors. We have investigated the optical properties of the dilute metallic phase in doped-SrTiO$_3$ using THz time-domain spectroscopy. At low frequencies the THz response exhibits a Drude-like form as expected for typical metal-like conductivity. We observed the frequency and temperature dependencies to the low energy scattering rate $Γ(ω, T) \propto (\hbarω)^2 + (p πk_BT)^2 $ expected in a conventional Fermi liquid, despite the fact that densities are too small to allow current decay through electron-electron scattering. However we find the lowest known $p$ values of 0.39-0.72. As $p$ is 2 in a canonical Fermi liquid and existing models based on energy dependent elastic scattering bound $p$ from below to 1, our observation lies outside current explanation. Our data also gives insight into the high temperature regime and shows that the temperature dependence of the resistivity derives in part from strong T dependent mass renormalizations.
title Anomalous frequency and temperature dependent scattering in the dilute metallic phase in lightly doped-SrTiO$_3$
topic Strongly Correlated Electrons
Superconductivity
url https://arxiv.org/abs/2402.18767