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arXiv · 2512.03108

Fermi-liquid behavior and characteristic temperature-dependent susceptibility in clean RuO$_2$ crystal

Shubhankar Paul·Atsutoshi Ikeda·Hisakazu Matsuki·Giordano Mattoni·Jörg Schmalian·Kunihiko Yamauchi·Chanchal Sow·Shingo Yonezawa·Yoshiteru Maeno
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Abstract

The magnetic nature of the altermagnet candidate RuO$_2$ remains under debate. It has been recently shown from quantum oscillations and angle-resolved photoemission spectroscopy (ARPES) that the high-quality RuO$_2$ bulk single crystal is a paramagnetic metal. Here we report the specific heat and magnetic susceptibility in ultra-clean RuO$_2$ single crystals with residual resistivity ratio up to 1200. The magnetic susceptibility increases with temperature and is phenomenologically fitted with an inclusion of $T\textrm{ln}(T/T_0)$ over a wide temperature range up to 400 K. In contrast, the energy dependence of the density of states and thermal activation of quasiparticles lead to a decrease with temperature. Such characteristic temperature dependence, similar to that observed in other $d$-electron metals, is attributable to an enhanced orbital contribution arising from lattice-expansion-induced changes in the band structure. The electronic specific heat, the magnetic susceptibility, and the $T^2$ coefficient in resistivity point to a weakly-correlated 3D Fermi-liquid state with a modest electron correlation, as supported by the Wilson and Kadowaki-Woods ratios.

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Shubhankar Paul, Atsutoshi Ikeda, Hisakazu Matsuki, Giordano Mattoni, Jörg Schmalian, Kunihiko Yamauchi, Chanchal Sow, Shingo Yonezawa, Yoshiteru Maeno. 2025-12-02. Fermi-liquid behavior and characteristic temperature-dependent susceptibility in clean RuO$_2$ crystal. https://doi.org/10.1103/vy8x-q3l6

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