2015/03/24 by Mohammad Alidoust, Klaus Halterman · 1 citation
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Bilayer #Ferromagnetism #Iron-based superconductors research #Josephson effect #Magnetic field #Magnetization #Physics of Superconductivity and Magnetism #Superconductivity #Supercurrent #Texture (cosmology) #Vortex #cond-mat.mes-hall #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1063/1.4908287
published as J. Appl. Phys. 117, 123906 (2015) · 25 pages, 17 figures - including detailed analytical and numerical calculations
openalex publication_date 2015/03/24 · arxiv created 2015/03/25 · arxiv updated 2015/04/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Using a spin-parameterized quasiclassical Keldysh-Usadel technique, we theoretically study supercurrent transport in several types of diffusive ferromagnetic (F)/superconducting (S) configurations with differing magnetization textures. We separate out the even-and odd-frequency components of the supercurrent within the low proximity limit and identify the relative contributions from the singlet and triplet channels. We first consider inhomogeneous one-dimensional Josephson structures consisting of a uniform bilayer magnetic S/F/F/S structure and a trilayer S/F/F/F/S configuration, in which case the outer F layers can have either a uniform or conical texture relative to the central uniform F layer. Our results demonstrate that for supercurrents flowing perpendicular to the F/F interfaces, incorporating a conical texture yields the most effective way to observe the signatures of long-ranged spin-triplet supercurrents. We also consider three different types of finite-sized two-dimensional magnetic structures subjected to an applied magnetic field normal to the junction plane: a S/F/S junction with uniform magnetization texture and two S/F/F/S configurations with differing F/F bilayer arrangements. In one case, the F/F interface is parallel with the S/F junction interfaces while in the other case, the F/F junction is oriented perpendicular to the S/F interfaces. We then discuss the proximity vortices and corresponding spatial maps of currents inside the junctions. For the uniform S/F/S junction, we analytically calculate the magnetic field induced supercurrent and pair potential in both the narrow and wide junction regimes, thus providing insight into the variations in the Fraunhofer diffraction patterns and proximity vortices when transitioning from a wide junction to a narrow one. Our extensive computations demonstrate that the induced long-range spintriplet supercurrents can deeply penetrate uniform F/F bilayers when spin-singlet supercurrents flow parallel to the F/F interfaces. This is in stark contrast to configurations where a spinsinglet supercurrent flows perpendicular to the F/F interfaces. We pinpoint the origin of the induced triplet and singlet correlations through spatial profiles of the decomposed total supercurrents. We find that the penetration of the long-range spin-triplet supercurrents associated with supercurrents flowing parallel to the F/F interfaces is more pronounced when the thicknesses of the F strips are unequal. Finally, if one of the S terminals is replaced with a finite-sized normal metal, we demonstrate that the corresponding experimentally accessible S/F/F/N spin valve presents an effective platform in which the predicted long-range effects can be effectively generated and probed.