Magnetic phase transitions in CePtSn under high pressure

CePtSn crystallizes in the orthorhombic TiNiSi-type structure. The compound undergoes two antiferromagnetic transitions at T-N = 7.5 K and T-M = 5 K, and it exhibits large magnetic and transport anisotropy. We report on measurements of the electrical resistivity of single-crystalline CePtSn as a function of temperature and magnetic field (i parallel to c axis, H parallel to a axis) performed under hydrostatic pressure up to 20 kbar. At ambient pressure, the overall temperature dependence indicates Kondo-type behavior in the presence of the crystal field. The application of pressure causes a reduction of the magnetoresistance effect. We find that the maximum in Delta rho / rho(B=0) is only 0.05 at 20 kbar, while it is about 0.15 at ambient pressure. On the other hand, application of hydrostatic pressure in CePtSn has little effect on both T-N and T-M. It initially increases both temperatures, but then reduces them again above 10 kbar. The results are discussed in terms of moment fluctuations and the variation due to increased 4f-ligand hybridization.