Effect of pressure on the electrical resistivity and magnetism in updsn

The electrical resistivity of a UPdSn single crystal exerted to various hydrostatic pressures was measured as a function of temperature and magnetic field. Clear anomalies in the temperature dependence of resistivity along the c-axis mark the magnetic phase transitions between paramagnetic and antiferromagnetic (AF) state at T _N and the AF1?AF2 transition at T ₁. Large negative magnetoresistance effects have been observed not only in the AF state as a result of the metamagnetic transition to canted structure at B _c , but also at temperatures far above T _N . The latter result is attributed to the existence of AF correlations or short range AF orderings in the paramagnetic range. The value of T _N increases with increasing applied pressure, whereas T ₁ simultaneously decreases. It is also found that B _c decreases with increasing pressure. As a consequence, the stability range of the AF-1 phase expands with applied pressure partially on account of the ground-state AF-2 phase.