Effects of pressure on the ferromagnetic state of the charge density wave compound SmNiC₂

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 T2 coefficient A near 3.8 GPa suggests abundant magnetic quantum fluctuations that arise from the possible presence of a FM quantum critical point.