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

Anna Elisabeth Böhmer (1) , Marcin Konczykowski (1) , Cornelis Jacominus van Der Beek (1)

1 LSI - Laboratoire des Solides Irradiés - Irradiated Solids Laboratory

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° with respect to the crystalline axes, rather than parallel to them.

Mots clés: First flux penetration; Bean-Livingston barrier; geometrical barrier; surface sheeth; aspect ratio; Andreev Bound states; d-wave superconductivity

Domaines: Supraconductivité [cond-mat.supr-con]

Anna Elisabeth Böhmer, Marcin Konczykowski, Cornelis Jacominus van Der Beek. Shape- and orientation-dependence of surface barriers in single crystalline d-wave Bi_2Sr_2CaCu_2O_8+delta. 2010. ⟨hal-00464055⟩