Mixed-State Hall Effect in an Extreme Type-II Superconductor

Abstract

Measurements of mixed-state transverse and longitudinal voltages at $T=1.2\ifmmode^\circ\else\textdegree\fi{}$K, $0lHl39$ kG, $0lJl800$ A/${\mathrm{cm}}^{2}$ on an extremely high-$\ensuremath{\kappa}$ type-II alloy superconductor Ti-16 at.% Mo ($\ensuremath{\kappa}=68$, ${T}_{c}=4.2\ifmmode^\circ\else\textdegree\fi{}$K, zero-temperature upper critical field ${H}_{c20}=63$ kG) show that the high-$J$, nearly $J$-independent, mixed-state Hall-angle tangent ${tan\ensuremath{\theta}}_{m}(H)$ is much larger than the normal-state value ${tan\ensuremath{\theta}}_{n}(H)$. At the highest applied magnetic field, the reduced Hall-angle tangent ${P}_{m}(\frac{H}{{H}_{k20}}=0.35)=\frac{[{tan\ensuremath{\theta}}_{m}(H=39 \mathrm{kG})]}{[{tan\ensuremath{\theta}}_{n}({H}_{k20})]}\ensuremath{\approx}0.6$, where ${H}_{k20}=111$ kG is determined by the measured reduced flux-flow resistivity $\frac{{\ensuremath{\rho}}_{f}(H)}{{\ensuremath{\rho}}_{n}}=\frac{H}{{H}_{k20}}$. This contrasts with previous results pertinent to pure or low-$\ensuremath{\kappa}$ materials where ${H}_{k20}\ensuremath{\approx}{H}_{c20}:{P}_{m}(0.35)\ensuremath{\approx}0.35$ (Bardeen-Stephen theory), (1) (Nozi\`eres-Vinen theory), 0.35 (Nb measurements of Fiory and Serin), (2) (Nb-Ta measurements of Niessen et al.).