Pressure-dependent magnetism and electrical resistivity of UFe4P

Abstract

${\mathrm{UFe}}_{4}$${\mathrm{P}}_{12}$ is the first reported uranium-based ferromagnetic semiconductor. The Curie temperature ${T}_{C}$ is 3.15 K, and the spontaneous magnetic moment ${\ensuremath{\sigma}}_{0}$ which at T=1.14 K was found to be \ensuremath{\simeq}1.0 ${\ensuremath{\mu}}_{B}$/(U atom), is associated entirely with the uranium ions. The electrical resistivity \ensuremath{\rho}(T) increases by nearly 7 orders of magnitude as temperature is decreased from room temperature to 4.2 K. The behavior of the ferromagnetic and electrical properties of ${\mathrm{UFe}}_{4}$${\mathrm{P}}_{12}$ in hydrostatic pressures up to 16 kbar is reported. Quasihydrostatic-pressure effects on \ensuremath{\rho}(T) to 100 kbar are also reported. Although ${T}_{C}$ increases sharply with increasing pressure at the rate ${\mathrm{dT}}_{C}$/dP=0.26 K/kbar (in contrast to similar data on the isomorphic ferromagnet ${\mathrm{NdFe}}_{4}$${\mathrm{P}}_{12}$, where ${\mathrm{dT}}_{C}$/dP=0.03 K/kbar), ${\ensuremath{\sigma}}_{0}$ decreases, (1/${\ensuremath{\sigma}}_{0}$)(d${\ensuremath{\sigma}}_{0}$/dp)=-0.007 ${\mathrm{kbar}}^{\mathrm{\ensuremath{-}}1}$. Hydrostatic and quasihydrostatic pressure have little effect on \ensuremath{\rho}(T).