Phase Diagram of the First-Order Vortex-Core Transition in SuperfluidHe3-B

The phase diagram of quantized vortices in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-$B$ has been obtained with two techniques. Our NMR measurements show that magnetization displays a pressure-dependent first-order phase change at $T_V\mathrm{}\left(P\right)\mathrm{}$. Our gyroscopic experiments reveal a transition curve $T_G\mathrm{}\left(P\right)\mathrm{}$ which marks an abrupt change in the critical velocity. Both curves show a weak magnetic field dependence, run similarly in the ($P$, $T$) plane, and seem to mark the same vortex-core transition.