Equilibrium and Dynamic Vortex States near Absolute Zero in a Weak Pinning Amorphous Film

By developing and employing a mode-locking measurement with pulsed currents, we successfully determine the dynamic melting field \(B_{\text{c,dyn}}^{\infty }(T)\) for a driven vortex lattice of an amorphous MoxGe1−x film in the limit of zero temperature (T → 0) and complete a dynamic as well as a static vortex phase diagram. At T = 0, the mixed state in the absence of pinning comprises vortex-lattice and quantum-vortex-liquid (QVL) phases, and the melting field separating the two phases is identified as \(B_{\text{c,dyn}}^{\infty }(0)\). Comparison of the dynamic and static phase diagrams reveals that, when the weak pinning is introduced into the pin-free system, a disordered phase emerges just above the vortex-lattice phase and a threshold field separating the two phases is slightly suppressed from \(B_{\text{c,dyn}}^{\infty }(0)\), indicative of defect-induced disordering of the lattice. By contrast, a melting field into QVL is much enhanced from \(B_{\text{c,dyn}}^{\infty }(0)\) up to a point near the ...