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arXiv · 1003.3938

Shape- and orientation-dependence of surface barriers in single crystalline d-wave Bi_2Sr_2CaCu_2O_8+delta

A. E. Boehmer·M. Konczykowski·C. J. van der Beek
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Abstract

Magneto-optical imaging and Hall-probe array magnetometry are used to measure the field of first flux entry, H_p, into the same Bi_2Sr_2CaCu_2O_8+delta single crystal cut to different crystal thickness-to-width ratios (d/w), and for two angles alpha between the edges and the principal in-plane crystalline (a,b) axes. At all temperatures, the variation with aspect ratio of H_p is qualitatively well described by calculations for the so-called geometric barrier [E.H. Brandt, Phys. Rev. B 60, 11939 (1999)]. However, the magnitude of H_p is strongly enhanced due to the square shape of the crystal. In the intermediate temperature regime (T < ~ 50 K) in which the Bean-Livingston barrier limits vortex entry, there is some evidence for a tiny crystal-orientation dependent enhancement when the sample edges are at an angle of 45\degree with respect to the crystalline axes, rather than parallel to them.

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A. E. Boehmer, M. Konczykowski, C. J. van der Beek. 2010-03-20. Shape- and orientation-dependence of surface barriers in single crystalline d-wave Bi_2Sr_2CaCu_2O_8+delta. https://arxiv.org/abs/1003.3938

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