Imprinting nanoporous alumina patterns into the magneto-transport of oxide superconductors

Abstract

We used oxygen ion irradiation to transfer the nanoscale pattern of a porous alumina mask into high-T(C) superconducting thin films. This causes a nanoscale spatial modulation of superconductivity and strongly affects the magneto-transport below T(C), which shows a series of periodic oscillations reminiscent of the Little-Parks effect in superconducting wire networks. This irradiation technique could be extended to other oxide materials in order to induce ordered nanoscale phase segregation.

Unusual magneto-transport of YBa2Cu3O7−δfilms due to the interplay of anisotropy, random disorder and nanoscale periodic pinning

“…Irradiation with O + ions (energy E = 110 keV) through the mask induces disorder in the YBCO film, in particular oxygen vacancies and interstitials. Note that contrary to masked ion milling techniques [52], here the material is not etched and the sample surface is not affected [53] by the ion irradiation: only point defects are created in the bulk of the material. These defects are strongly concentrated in the regions directly exposed to the ion beam through the mask holes.…”

Strong field-matching effects in superconducting YBa2Cu3O7−δSwiecicki1, Ulysse2, Wolf3 et al. 2012Phys. Rev. B545523View full textAdd to dashboardCite

“…by the amplitude of the field matching effects observed in the magnetotransport-is generally found to be much weaker in high-T C (e.g. YBa 2 Cu 3 O 7-δ ) 18,21,22 than in low-T C superconductors (e.g. Nb) 1 .…”

“…Therefore the ions are fully stopped by the mask and reach the YBCO film only through the mask holes. O + ion bombardment does not change the YBCO surface morphology 21 , but creates point defects within the bulk of the material 21 .…”

“…While much of the progress in this area has been done with low critical-temperature (T C ) superconductors 1,2,4,5,8,10,11 , extending this research to high-T C materials 6,7,14,[18][19][20][21][22] is particularly interesting. For the latter, the interplay between the artificial ordered pinning, the characteristic anisotropy, and the strong thermal fluctuations predisposes to a richer phenomenology.…”

Nanowall pinning for enhanced pinning force in YBCO films with nanofabricated structures

“…Thus, pinning effects by ordered arrays of defects have been intensively studied in both conventional low temperature superconductors [17][18][19][20][21][22] and high temperature superconductors [23][24][25][26][27] for several decades. Recently, YBCO films that contained periodic vortex pinning arrays created via masked ion irradiation demonstrated strong matching-field effects verifying the prevalence of periodic pinning over intrinsic random pinning [23,28]. Also, guided vortex motion in YBCO film with asymmetric artificial defects created by FIB patterning, recently confirmed that higher pinning forces than those from intrinsic defects, could be achieved by precise artificial pinning potential designs [24].…”