First-order phase transition of the vortex lattice in twinned YBa2Cu3O7 single crystals in tilted magnetic fields

Article

关键词: HIGH-TEMPERATURE SUPERCONDUCTORS;    BOSE-GLASS TRANSITION;    MELTING TRANSITION;    UNTWINNED YBA2CU3O7-DELTA;    COLUMNAR DEFECTS;    FLUX-LATTICE;    LIQUID-STATE;    C DIRECTION;    LATENT-HEAT;    DISORDER;   

DOI  :  10.1103/PhysRevB.61.12427

来源: SCIE

【 摘 要 】

We present an exhaustive analysis of transport measurements performed in twinned YBa2Cu3O7 single crystals which establishes that the vortex solid-liquid transition is first order when the magnetic field H is applied at an angle theta away from the direction of the twin planes. We show that the resistive transitions are hysteretic and the V-I curves are nonlinear, displaying a characteristic S shape at the melting line H-m(T), which scales as epsilon(theta)H-m(T,theta), where epsilon(theta) is the anisotropy factor. These features are gradually lost when the critical point H*(theta) is approached. Above H*(theta) the V-I characteristics show a linear response in the experimentally accessible V-l window, and the transition becomes reversible. Finally we show that the first order phase transition takes place between a highly correlated Vortex liquid in the field direction and a solid state of unknown symmetry. As a consequence, our data support the scenario for a ver-tex-line melting in twinned YBa2Cu3O7 crystals in contrast to a vortex sublimation as recently suggested for untwinned La2-xSrxCuO4, YBa2Cu3O7 and Bi2Sr2CaCu2O8 [T. Sasagawa et al., Phys. Rev. Lett. 80, 4297 (1998)].

【 授权许可】

Free