Magnetoresistance of CePtSi_(2) under high pressure

摘要

The electrical resistivity and magnetoresistance (MR) of CePtSi_(2) have been measured under high pressure in order to clarify the electronic state around T_(N) approx 0 K. (rho)_(mag)(T) at ambient pressure, defined as (rho)_(mag) velence rho(CePtSi_(2)) - rho(LaPtSi_(2)), increases with decreasing temperature until it shows a maximum around 28 K((velence)T_(2)) and a small shoulder around 5 K((velence)T_(1)). T_(1) increases with applying pressure and merges into T_(2) around 1.0 GPa. T_(2) is almost constant up to 1.0 GPa, but increases rapidly with applying pressure above 1.0 GPa. Negative MR was observed up to 2.4 GPa at 4.2 K. The magnitudes of MR at 9 T are -24.5percent and -7.9percent at 0.1 and 2.4 GPa, respectively. By applying the Okiji-Kawakami model to the present results, it is found that the Kondo temperature T_(K) increases with increasing pressure. The slope of pressure dependence of MR ratio at 9 T changes slightly around 1.0 GPa. These results suggest a pressure-induced crossover in the electronic states around 1.0 GPa.