London and Campbell penetration depths in single crystals of Mo₈Ga₄₁ superconductor

Zero-field London penetration depth, λ_L(T), and Campbell penetration depth, λ_C(T), in DC magnetic fields up to 8 T, was measured in single crystals of Mo₈Ga₄₁ superconductor using tunnel diode resonator (TDR). In addition, the absolute value, λ_L(0) = 260 ± 10 nm, was extracted from the lower critical field, H_c1 , measurements using NV-centers in diamond optical magnetometry. The obtained superfluid density, ρ_s , follows very well clean isotropic single-gap weak-coupling BCS s−wave curve in the whole temperature range. The Campbell penetration depth was used to extract magnetic relaxation-free critical current density as a function of temperature and magnetic field. The results and the constructed vortex phase diagram are compared to other magnetic measurements of this and comparable superconductors.