Effect of superconductivity on non-uniform magnetization in dirty SF junctions

Fuente: arXiv
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Main Authors: Levin, A. V., Ostrovsky, P. M.
Format: Preprint
Published: 2025
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author Levin, A. V.
Ostrovsky, P. M.
author_facet Levin, A. V.
Ostrovsky, P. M.
contents We study proximity effect in a tunnel junction between a bulk superconductor and a thin disordered ferromagnetic layer on its surface. Cooper pairs penetrating from the superconductor into the ferromagnet tend to destabilize its uniform magnetic order. The competition of this effect and the intrinsic magnetic stiffness of the ferromagnet leads to a second order phase transition between uniform and non-uniform magnetic states. Using the quasiclassical Usadel equation, we derive the Landau functional for this transition and construct the complete phase diagram of the effect. We identify a special point of "resonance" at which the characteristic energy scale of the proximity effect equals the exchange field of the ferromagnet. At this point, the uniform magnetic state is unstable even in the limit of large stiffness. We further explore the parameter regime far beyond the transition and determine the properties of the resulting strongly non-uniform magnetic state.
format Preprint
id arxiv_https___arxiv_org_abs_2512_08044
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Effect of superconductivity on non-uniform magnetization in dirty SF junctions
Levin, A. V.
Ostrovsky, P. M.
Disordered Systems and Neural Networks
Mesoscale and Nanoscale Physics
We study proximity effect in a tunnel junction between a bulk superconductor and a thin disordered ferromagnetic layer on its surface. Cooper pairs penetrating from the superconductor into the ferromagnet tend to destabilize its uniform magnetic order. The competition of this effect and the intrinsic magnetic stiffness of the ferromagnet leads to a second order phase transition between uniform and non-uniform magnetic states. Using the quasiclassical Usadel equation, we derive the Landau functional for this transition and construct the complete phase diagram of the effect. We identify a special point of "resonance" at which the characteristic energy scale of the proximity effect equals the exchange field of the ferromagnet. At this point, the uniform magnetic state is unstable even in the limit of large stiffness. We further explore the parameter regime far beyond the transition and determine the properties of the resulting strongly non-uniform magnetic state.
title Effect of superconductivity on non-uniform magnetization in dirty SF junctions
topic Disordered Systems and Neural Networks
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2512.08044