The anomalous magnetic properties of $CaRuO_3$ probed by AC and DC magnetic measurements and by low Ti impurity doping

TL;DR

This study investigates the magnetic behavior of CaRuO3 and Ti-doped CaRuO3, revealing critical spin fluctuation slowing down near zero temperature and identifying crossover regimes linked to quantum criticality.

Contribution

It provides detailed AC and DC magnetic susceptibility measurements of CaRuO3 and Ti-doped CaRuO3, highlighting subtle magnetic features associated with quantum critical behavior.

Findings

Frequency-dependent AC susceptibility below 40 K

Curvature change around 12 K indicating critical slowing down

Enhanced magnetic response in Ti-doped sample at specific temperatures

Abstract

Calcium ruthenate ($CaRuO_3$) is widely believed to be located close to a quantum critical point due to the strong non-Fermi-liquid behavior expressed in the temperature dependence of electronic transport, specific heat, optical conductivity, etc. However, the corresponding anomalous behavior, marking crossover temperature regimes in the magnetic response of $CaRuO_3$, is still lacking. Here we report detailed AC and DC magnetic susceptibility measurements of $CaRuO_3$ and $CaRu_{0.97}Ti_{0.03}O_3$. The AC magnetic susceptibility measurements of the $CaRuO_3$ show a slight dependence on the frequency of AC magnetic field below ~ 40 K, and an additional subtle change of curvature around 12 K. We interpret these results as a critical slowing down of spin fluctuations towards T=0 K. We confirm these observations by magnetic measurements of $CaRu_{0.97}Ti_{0.03}O_3$, which show a pronounced magnetic response corresponding to the above temperatures.