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Excess currents in planar Ba(Fe 1 − x Co x ) 2 As 2 /TiO x /Pb Josephson junctions
Author(s) -
Döring Sebastian,
Reifert David,
Hasan Noor,
Schmidt Stefan,
Schmidl Frank,
Tympel Volker,
Kurth Fritz,
Iida Kazumasa,
Holzapfel Bernhard,
Wolf Thomas,
Seidel Paul
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201552307
Subject(s) - josephson effect , materials science , planar , condensed matter physics , microwave , electrode , current (fluid) , thin film , biasing , optoelectronics , superconductivity , analytical chemistry (journal) , voltage , chemistry , nanotechnology , physics , computer graphics (images) , quantum mechanics , computer science , chromatography , thermodynamics
We prepared planar hybrid Josephson junctions using Co‐doped BaFe2 As2 thin films and polished single crystals as base electrode, sputtered, and subsequently oxidized titanium layers as barrier and a counter electrode from evaporated lead. On all junctions, RCSJ‐like current–voltage characteristics could be observed. The obtained I c R n products at 4.2 K range up to 95 μ V for thin film junctions and up to 1.15 mV for junctions on single crystals. For most of the junctions, an excess current with variable contribution to the total current could be observed. Unusual temperature dependencies are discussed for the critical and the excess currents, respectively. Investigations of the junctions under microwave irradiation were performed, therein Shapiro steps up to high orders and very clear modulations of the steps could be observed. Additionally, the origin of the excess current is discussed with respect to the microwave dependence. Furthermore, instead of a single junction, a network‐like modulation behavior of the critical current in magnetic fields was observed.