Extended snapshots of glassy vortex phases

YANINA FASANO

Lake Yamanaka

Workshop; Charla invitada 12th International Workshop on Vortex Matter in Superconductors, Yamanaka, Jap’on; 2009

University of Tokyo

We studied the ¯eld-evolution of the topological properties of glassy vortex phases bymeans of extended scanning-tunnelling-spectroscopy (STS)1 and magnetic-decoration2 imag-ing of the vortex structure. This investigation was performed in two di®erent systems: thelow-Tc Chevrel phase superconductor SnMo6S8 and the electron-irradiated high-Tc Bi2Sr2CaCu2O8¡±compound. We obtained the ¯rst extended snapshots of the vortex glass revealing that thisphase is not amorphous and posses intermediate-range positional order.For SnMo6S8 we have obtained maps of around 100 vortices from 2 to 9Tesla by perform-ing STS at 400 mK. The orientational and positional orders at ¯elds larger than 5Tesla aredepleted with respect to the 2Tesla structure and dislocations proliferate, but no amorphousstructure is observed at high ¯elds.3In the case of electron-irradiated Bi2Sr2CaCu2O8¡±, we have obtained maps of thousandsof vortices in a sample displaying an order-disorder transition at 74 Oe4 by means of magnetic-decoration imaging at 4.2 K. We obtained extended images of both, the vortex and Braggglass phases, varying the applied ¯eld between 30 and 85 Oe. For every ¯eld we comparedthe structural properties of vortex matter nucleated in irradiated and pristine twin-samples.The vortex glass phase of the irradiated samples is not amorphous although the positionalorder is suppressed compared with that of the Bragg glass.[1] Â. Fischer, M. Kugler, I. Maggio-Aprile, Ch. Berthod, and Ch. Renner, Rev. Mod. Phys.79, 353 (2007).[2] Y. Fasano and M. Menghini, Supercond. Science and Tech. 21, 023001 (2008).[3] A.P. Petrovi¶c, Y. Fasano, R. Lortz, C. Senatore, A. Demuer, A.B. Antunes, A. Par¶e, D.Salloum, P. Gougeon, M. Potel, and Â. Fischer, condmat:0903.2389 .[4] M. Konczykowski, C.J. van der Beek, A.E. Koshelev, V. Mosser, M. Li, and P. H. Kes,J. Phys.: Conf. Ser. 150, 052119 (2009).