Superconducting intermediate state of white tin studied by muon-spin-rotation spectroscopy

Abstract

The local magnetic field in the bulk of superconducting single crystal $\ensuremath{\beta}$ tin was measured near and across the transition between the normal (N) and intermediate (I) state at $T=0.08 \mathrm{K}.$ With varying applied field ${H}_{a},$ the data indicate a reversible phase transition within the I state at ${H}_{t}\ensuremath{\approx}295 \mathrm{Oe},$ interpreted as a transition from the laminar to a tubular structure. Near the $\stackrel{\ensuremath{\rightarrow}}{I}N$ transition, occurring at ${H}_{\mathrm{cI}}{=0.98H}_{c0}=300 \mathrm{Oe},$ the field B in the N domains is strongly inhomogeneous with $\overline{B}<{H}_{c0},$ it grows with the decrease of ${H}_{a}$ towards the value ${H}_{c0}=305.5\ifmmode\pm\else\textpm\fi{}0.5 \mathrm{Oe}.$ On lowering ${H}_{a}$ in the N state, a large ``field supercooling'' $(\ensuremath{\delta}{H/H}_{c}\ensuremath{\approx}6%)$ of this state was observed.