Effects of pressure on the ferromagnetic state of the CDW compound SmNiC2

TL;DR

This study investigates how applying pressure up to 5.5 GPa affects the charge-density-wave and ferromagnetic phases of SmNiC2, revealing significant changes in transition temperatures and potential quantum critical behavior.

Contribution

It provides new insights into the pressure-induced evolution of CDW and FM phases in SmNiC2, highlighting the emergence of quantum fluctuations and phase transition bifurcation.

Findings

CDW transition temperature increases sharply above 2.18 GPa

Ferromagnetic transition bifurcates into two phases under pressure

Enhanced magnetic fluctuations near 3.8 GPa suggest quantum criticality

Abstract

We report the pressure response of charge-density-wave (CDW) and ferromagnetic (FM) phases of the rare-earth intermetallic SmNiC2 up to 5.5 GPa. The CDW transition temperature (T_{CDW}), which is reflected as a sharp inflection in the electrical resistivity, is almost independent of pressure up to 2.18 GPa but is strongly enhanced at higher pressures, increasing from 155.7 K at 2.2 GPa to 279.3 K at 5.5 GPa. Commensurate with the sharp increase in T_{CDW}, the first-order FM phase transition, which decreases with applied pressure, bifurcates into the upper (T_{M1}) and lower (T_c) phase transitions and the lower transition changes its nature to second order above 2.18 GPa. Enhancement both in the residual resistivity and the Fermi-liquid T^2 coefficient A near 3.8 GPa suggests abundant magnetic quantum fluctuations that arise from the possible presence of a FM quantum critical point.