μSR study of CeRhIn₅ under applied pressure

At ambient pressure CeRhIn₅ is an incommensurate antiferromagnet with Néel temperature T_N = 3.8 K. The application of pressure reduces T_N and yields (1) a state in which AFM coexists with superconductivity, and then (2) a superconducting state in the absence of AFM. We report transverse-field muon spin relaxation (μSR) measurements at pressures 2.07 and 2.26 GPa in the pure superconducting state of single-crystalline CeRhIn₅, which has a tetragonal structure. μSR is sensitive to the local field distribution produced by the vortex lattice in a mixed superconducting state, allowing a measurement of the magnetic field penetration depth λ(T). We measured λ_ab(T) for applied field along the c-axis as a function of temperature T, and find λ_ab(0) = 372(5) nm and 338(6) nm for P = 2.07 GPa and 2.26 GPa, respectively. The temperature dependence of the superfluid density ρ_s(T) ∝ λ⁻²(T) was found to be ρ_s(T) ∝ Tⁿ with n = 1.9(2).