MFM study of the Flux Line Lattice in the b-Bi2Pd superconductor

A. CORREA-ORELLANA; R. F. LUCCAS; J. AZPEITIA; F. J. MOMPEAN; M. GARCÍA- HERNANDEZ; H. SUDEROW; C. MUNUERA

El Escorial

Congreso; VORTEX 2015; 2015

b-Bi2Pd is a multiband superconductor that crystallizes in layered tetragonal structure. It is a metastable phase below 750 K with a TC of around 5.1 K [1]. In this work, we present results obtained using magnetic force microscopy MFM in the mixed state b-Bi2Pd. Crystals were grown from high purity Bi and Pd. The good quality of the crystals was confirmed with X-ray diffraction, resistivity and magnetic measurements. We measure down to 2.5 K using a commercial MFM (Nanomagnetics Ltd) within a home-made 3-axis superconducting coil [2]. We report in this work real space images of the Abrikosov lattice on b-Bi2Pd measured on atomically flat terraces. The terraces are several microns large, separated by nanometric steps. Images of a hexagonal flux line lattice have been recorded in large regions when applying a magnetic field perpendicular to the surface. We have investigated the structure and orientation of the vortex lattice as well as its switching behavior. We observe, under certain conditions, vortices that are not round.This could be associated to the geometry of the magnetization of the MFM tip. Furthermore, we are studying the effect of graphene deposited on top of the b-Bi2Pd crystals