High pressure studies on the ferromagnetic dense Kondo systems CeRh3B2 and UCu2Ge2

Abstract

The dependence of the Curie temperature of the anomalous ferromagnets UCu2Ge2 and CeRh3B2 on hydrostatic pressure to 11 GPa is determined using a diamond‐anvil cell loaded with dense helium as pressure medium. A sensitive primary/secondary coil system allows the detection of the ferromagnetic transition in the ac susceptibility for tiny samples with less than 1 μ mass. The Curie temperatures of the above two compounds, Tc≊110 K and 118 K, both increase initially under pressure but pass through maxima at 8 GPa and 2 GPa, respectively, before falling rapidly at higher pressures. We take this as evidence that both compounds behave as dense Kondo system, where Tc depends on the exchange coupling J according to a magnetic phase diagram originally proposed by Doniach.