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Critical Currents and Order-Disorder Phase Transition in the Vortex States of YBa2Cu4O8 with Chemically Introduced Disorder

M. Angst·S. M. Kazakov·J. Karpinski·A. Wisniewski·R. Puzniak·M. Baran
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Abstract

A series of YBa_{2-x}Sr_xCu_4O_8 single crystals was measured to study the influence of site disorder on the transition line Hss(T) between quasi-ordered vortex lattice and highly disordered vortex glass, as well as on the maximum critical current density within the glass phase, jcmax. When 32% of Ba is replaced by Sr, jcmax is an order of magnitude higher than in the unsubstituted compound. In contrast, the transition field Hss first drops by a factor of about five with a substitution of just 10% of Sr for Ba, and then remains approximately constant for higher Sr contents. Our results indicate that in very clean systems the order-disorder transition is affected very strongly by any crystallographic disorder, while above a certain threshold it is relatively robust with respect to additional disorder. In all substituted crystals Hss monotonically decreases with an increase of temperature.

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M. Angst, S. M. Kazakov, J. Karpinski, A. Wisniewski, R. Puzniak, M. Baran. 2001-12-15. Critical Currents and Order-Disorder Phase Transition in the Vortex States of YBa2Cu4O8 with Chemically Introduced Disorder. https://doi.org/10.1103/physrevb.65.094518

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