Regular Article

Two-band superconducting square with a central defect: role of the deGennes extrapolation length

¹ Departamento de Física, Universidade Federal de Mato-Grosso, Cuiabá, Brasil
² CMULTI, Universidade Federal do Acre-AC, Cruzeiro do Sul, Brasil
³ Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia
⁴ Foundation of Researchers in Science and Technology of Materials – FORISTOM, Bucaramanga, Colombia

^a e-mail: thiago.nunes@fisica.ufmt.br

Received: 28 August 2019
Received in final form: 20 November 2019
Published online: 13 April 2020

Abstract

We present the influence of the deGennes extrapolation length on the vortex matter in a two band superconducting square with a central defect. This is determined by considering different values of the de Gennes extrapolation length b on the lateral surface of the sample. Our investigation was carried out by solving the two-dimensional time-dependent Ginzburg-Landau equations for a two-band system (2B-TDGL). We studied the density, magnetization, vorticity, and critical fields of the superconducting electrons as functions of the external applied magnetic field for different values of b on the surfaces of the sample and different sizes of the internal square defect. We show an unconventional vortex state due to the repulsive (attractive) short- (long-) range potential between the vortices. Finally, we show that at the limit of the thin film, a two-band system behaves like a three-band system.