Observation of the vortex-glass transition in YBa2Cu3O7 by phase-resolved current-voltage measurements

W. Lang, C. Fussenegger, S. Proyer, E. Stangl, D. Bäuerle

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed


We report on investigations of the current-dependent ac impedance Z at 17 Hz of a YBa2Cu3O7 thin-film microbridge in magnetic fields from 1 to 8 T. A phase-sensitive lock-in technique was applied and supplemented by a pulsed method for high current densities. Above the vortex-glass transition temperature T-g a constant Z(j) is observed with low current densities j, and a power-law behavior at high currents. Below T-g, the curvature of the Re Z vs. J curve is negative in a log-log plot. The Re Z(j) isotherms can be collapsed onto two universal scaling functions according to the predictions of the vortex-glass model. Close to and below T-g, a phase lag between current and voltage appears, which saturates to finite values at low j and to zero at high j. The phase lag within the constant-Z(j) region remains below the critical value, predicted theoretically by Dorsey, if T > T-g and approaches 90 degrees at T <T-g indicating the freezing of the vortices into the dissipation-free vortex-glass state.
Seiten (von - bis)13-18
FachzeitschriftZeitschrift für Physik B - Condensed Matter
PublikationsstatusVeröffentlicht - 1996

ÖFOS 2012

  • 103018 Materialphysik