Chemical pressure in SmNiC2-xBx compounds: evidence of a quantum critical behavior

We studied the effect of carbon substituted by boron on polycrystalline samples of SmNiC2 in the B content range 0 <= x <= 0.200. The structural parameters were determined from x-ray measurements by Rietveld analysis. The structural analysis shows that the cell volume increases as the B content increases indicating that the substitution produces an internal pressure. The samples were studied by resistance as a function of temperature from room temperature down to 2 K. The transition temperature of the charge density wave, T-CDW = 148 K, decreases with an increment of B until the transition vanishes in the resistance measurements. At the same time, the ferromagnetic transition temperature changes showing a tiny dome with the B content, with a maximum transition temperature of similar to 23.1 K. In addition, the resistance behaviour above the charge density wave is linear in temperature and this behaviour persists until the charge density wave disappears, suggesting that the system is a non-Fermi liquid. The resulting temperature-boron content phase-diagram indicates a quantum critical behaviour.