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

B. Maiorov·G. Nieva·E. Osquiguil
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Abstract

We present an exhaustive analysis of transport measurements performed in twinned YBa2Cu3O7 single crystals which stablishes 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 non-linear, displaying a characteristic s-shape at the melting line Hm(T), which scales as epsilon(theta)Hm(T,theta). 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-I 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, the available data support the scenario for a vortex-line melting rather than a vortex sublimation as recently suggested [T.Sasagawa et al. PRL 80, 4297 (1998)].

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B. Maiorov, G. Nieva, E. Osquiguil. 1999-08-30. First order phase transition of the vortex lattice in twinned YBa2Cu3O7 single crystals in tilted magnetic fields. https://doi.org/10.1103/physrevb.61.12427

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