High-pressure study of the anomalous ferromagnetCeRh3B2to 7 GPa: Comparison with substitutional experiments

The ferromagnet ${\mathrm{CeRh}}_3$ ${\mathrm{B}}_2$ has a Curie temperature ${\mathit{T}}_{\mathit{C}}$ near 117 K, two orders of magnitude higher than anticipated from simple de Gennes scaling. To shed light on the nature of the anomalous magnetic state, the hydrostatic pressure dependence of ${\mathit{T}}_{\mathit{C}}$ was measured to 7.0 GPa using a diamond-anvil cell with dense He as pressure medium. As a function of pressure, ${\mathit{T}}_{\mathit{C}}$(P) initially increases at the rate of 1.0 K/GPa but then passes through a maximum near 2.5 GPa and falls rapidly at higher pressures. This qualitative behavior can be accounted for by a simple phase diagram proposed some time ago by Doniach for dense Kondo systems. This diagram is also used to compare the evolution of magnetism in related substitutional compounds to that for ${\mathrm{CeRh}}_3$ ${\mathrm{B}}_2$ under pressure. For selected Ce compounds, a universal relation between the coupling strength J and the ordering temperature ${\mathit{T}}_{\mathit{C}}$ is found.