Unconventional critical state in YBa₂Cu₃O_7-δ thin films with a vortex-pin lattice fabricated by masked He⁺ ion beam irradiation

Author(s)

Georg Zechner, Kristijan Luka Mletschnig, Wolfgang Lang, Meirzhan Dosmailov, Marius Aurel Bodea, Johannes David Pedarnig

Abstract

Thin superconducting YBa₂Cu₃O_7-δ films are patterned with a vortex-pin lattice consisting of columnar defect regions (CDs) with 180 nm diameter and 300 nm spacing. They are fabricated by irradiation with 75 keV He⁺ ions through a stencil mask. Peaks of the critical current reveal the commensurate trapping of vortices in domains near the edges of the sample. Upon ramping an external magnetic field, the positions of the critical current peaks are shifted from their equilibrium values to lower magnetic fields in virgin and to higher fields in field-saturated down-sweep curves, respectively. Based on previous theoretical predictions, this irreversibility is interpreted as a nonuniform, terrace-like critical state, in which individual domains are occupied by a constant number of vortices per pinning site. The magnetoresistance, probed at low current densities, is hysteretic and angle dependent and exhibits minima that correspond to the peaks of the critical current. The minima's positions scale with the component of the magnetic field parallel to the axes of the CDs, as long as the tilted vortices can be accommodated within the CDs. This behavior, different from unirradiated films, confirms that the CDs dominate the pinning.

Organisation(s)

Electronic Properties of Materials

External organisation(s)

Johannes Kepler Universität Linz

Journal

Superconductor Science & Technology

Volume

31

No. of pages

8

ISSN

0953-2048

DOI

https://doi.org/10.1088/1361-6668/aaacc1

Publication date

02-2018

Peer reviewed

Yes

Austrian Fields of Science 2012

103015 Condensed matter, 103033 Superconductivity, 210004 Nanomaterials

Keywords

ASJC Scopus subject areas

Condensed Matter Physics, Ceramics and Composites, Metals and Alloys, Materials Chemistry, Electrical and Electronic Engineering

Portal url

https://ucris.univie.ac.at/portal/en/publications/unconventional-critical-state-in-yba2cu3o7-thin-films-with-a-vortexpin-lattice-fabricated-by-masked-he-ion-beam-irradiation(92865ff1-bd0a-4c8f-8c03-a8c250122b93).html