Magnetoresistance of CePtSi₂ under high pressure

Abstract

The electrical resistivity and magnetoresistance (MR) of CePtSi₂ have been measured under high pressure in order to clarify the electronic state around T _N ∼ 0 K. ρ_mag (T) at ambient pressure, defined as ρ_mag = ρ(CePtSi₂)−ρ(LaPtSi₂), increases with decreasing temperature until it shows a maximum around 28 K(=T ₂) and a small shoulder around 5 K(=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−24.5% and−7.9% 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.

Keywords:

• Magnetoresistance
• Electrical resistivity
• Pressure effect
• Kondo effect
• Heavy fermion substance