Pressure dependence of dilute Gd moments in Pr-based ferromagnets

Abstract

Shender has predicted that in highly enhanced crystalline electric field singlet ground state systems there can be a magnetic polarization in the vicinity of well-localized 4f magnetic ions such as Gd. This is an f-electron analogue of the well-known giant Fe moment in Pd, where d-electrons are involved. A search for such moments in weakly ferromagnetic Pr-based compounds has been undertaken using pressure-dependent magnetization and electrical resistivity ρ. The systems investigated are (1) Gd in Pr3S4 (TC = 2.5 K) and (2) Gd in Pr3Tl (TC = 11 K). For both hosts hydrostatic pressures P<10 kbar cause a transition from ferromagnetism to enhanced paramagnetism. For (Pr0.98Gd0.02)3S4, a spinglass-like transition occurs at 8.5 K. The high field moment shows a large nonlinear decrease with increasing pressure. For Gd in Pr3Tl, TC increases rapidly but nonlinearly with Gd concentration and anomalies are seen in ρ and dρ/dT which are characteristic of ferromagnetic transitions.