Pressure-Induced Three-Dimensional Ferromagnetic Correlations in the Giant Magnetocaloric CompoundGd5Ge4

Abstract

The giant magnetocaloric compound ${\mathrm{G}\mathrm{d}}_5{\mathrm{G}\mathrm{e}}_4$ is the only member of the ${\mathrm{G}\mathrm{d}}_5({\mathrm{S}\mathrm{i}}_x{\mathrm{G}\mathrm{e}}_{1-x}{)}_4$ family where three-dimensional exchange interactions between two-dimensional correlated layers of the crystallographic structure are so weak that spontaneous ferromagnetism does not set in at any temperature. In this Letter we explore the possibility to reach the ferromagnetic state by application of hydrostatic pressure. Linear thermal expansion and magnetic measurements under pressure reveal that the reduction of the unit cell volume induces a spatially phase-segregated ground state below 10 kbar.