Campbell penetration depth in single crystals of miassite Rh₁₇S₁₅ superconductor

The magnetic penetration depth, λ(T) was measured in single crystal miassite Rh₁₇S₁₅ in two different orientations, [100] and [111], using a 14 MHz tunnel diode resonator (TDR). In the presence of a DC magnetic field λ(T) is mainly determined by the Campbell penetration depth, λ_C(T), which characterizes the penetration of a small AC magnetic field mediated by the Abrikosov vortex lattice. Surprisingly for this cubic system, the λ_C (T) shows substantial anisotropy in orientations with a peak effect in λ_C(T) observed in the [111] orientation. Furthermore, nonmagnetic disorder induced by 2.5 MeV electron irradiation results in a large peak effect in λ_C (T). The critical current density is estimated from λ_C(T) as a function of temperature and magnetic field and indicates the static origin of the peak effect (not coming from magnetic relaxation). The results from the TDR measurement are compared with the DC magnetization measurements.