Upper critical fields in normal metal–superconductor–normal metal trilayers

Abstract The role of spin orbit interaction in superconducting proximity effect is an area of intense research effort. Recent theoretical and experimental works investigate the possible role of spin–orbit interaction in generating spin-triplet pair correlations. In this work, we present an experimen...

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Main Authors: Kelsey B. Robbins, Pukar Sedai, Alexandra J. Howzen, Robert M. Klaes, Reza Loloee, Norman O. Birge, Nathan Satchell
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-025-98332-1
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author Kelsey B. Robbins
Pukar Sedai
Alexandra J. Howzen
Robert M. Klaes
Reza Loloee
Norman O. Birge
Nathan Satchell
author_facet Kelsey B. Robbins
Pukar Sedai
Alexandra J. Howzen
Robert M. Klaes
Reza Loloee
Norman O. Birge
Nathan Satchell
author_sort Kelsey B. Robbins
collection DOAJ
description Abstract The role of spin orbit interaction in superconducting proximity effect is an area of intense research effort. Recent theoretical and experimental works investigate the possible role of spin–orbit interaction in generating spin-triplet pair correlations. In this work, we present an experimental survey of thin normal metal–superconductor–normal metal trilayers with Nb superconductor and Al, Ti, Cu, Pt, Ta, and Au normal metals, along with single layers of Nb as reference. We aim to probe the role of spin–orbit interaction and resistivity on the normal metal proximity effect through measurements of the upper critical field. We find that the upper critical fields of the trilayers are lower than that of a single layer Nb reference sample, and that the trilayers with higher resistivity metals, Ti, Pt, and Ta, behave as 2-dimensional superconductors. At low applied in-plane magnetic fields and temperatures close to the zero field transition temperature, we find a possible deviation from 2-dimensional to 3-dimensional behavior in the Ti and Pt trilayers. We also find that compared to single layer Nb films, all of our trilayers show a greater suppression of critical temperature during rotation from an in-plane to an out-of-plane applied magnetic field, with the greatest suppression observed in trilayers with Au or Al. This suppression of the critical temperature under field rotation might appear analogous to the colossal spin valve effect that can be achieved in systems with ferromagnetic materials; however, in our trilayers, only conventional orbital screening contributions to the suppression are present and the additional suppression is not present in the absence of applied magnetic field.
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spelling doaj-art-2c9bc153fabd4ee98fef80e28689994d2025-08-20T02:17:54ZengNature PortfolioScientific Reports2045-23222025-04-011511910.1038/s41598-025-98332-1Upper critical fields in normal metal–superconductor–normal metal trilayersKelsey B. Robbins0Pukar Sedai1Alexandra J. Howzen2Robert M. Klaes3Reza Loloee4Norman O. Birge5Nathan Satchell6Department of Physics, Texas State UniversityDepartment of Physics, Texas State UniversityDepartment of Physics, Texas State UniversityDepartment of Physics and Astronomy, Michigan State UniversityDepartment of Physics and Astronomy, Michigan State UniversityDepartment of Physics and Astronomy, Michigan State UniversityDepartment of Physics, Texas State UniversityAbstract The role of spin orbit interaction in superconducting proximity effect is an area of intense research effort. Recent theoretical and experimental works investigate the possible role of spin–orbit interaction in generating spin-triplet pair correlations. In this work, we present an experimental survey of thin normal metal–superconductor–normal metal trilayers with Nb superconductor and Al, Ti, Cu, Pt, Ta, and Au normal metals, along with single layers of Nb as reference. We aim to probe the role of spin–orbit interaction and resistivity on the normal metal proximity effect through measurements of the upper critical field. We find that the upper critical fields of the trilayers are lower than that of a single layer Nb reference sample, and that the trilayers with higher resistivity metals, Ti, Pt, and Ta, behave as 2-dimensional superconductors. At low applied in-plane magnetic fields and temperatures close to the zero field transition temperature, we find a possible deviation from 2-dimensional to 3-dimensional behavior in the Ti and Pt trilayers. We also find that compared to single layer Nb films, all of our trilayers show a greater suppression of critical temperature during rotation from an in-plane to an out-of-plane applied magnetic field, with the greatest suppression observed in trilayers with Au or Al. This suppression of the critical temperature under field rotation might appear analogous to the colossal spin valve effect that can be achieved in systems with ferromagnetic materials; however, in our trilayers, only conventional orbital screening contributions to the suppression are present and the additional suppression is not present in the absence of applied magnetic field.https://doi.org/10.1038/s41598-025-98332-1
spellingShingle Kelsey B. Robbins
Pukar Sedai
Alexandra J. Howzen
Robert M. Klaes
Reza Loloee
Norman O. Birge
Nathan Satchell
Upper critical fields in normal metal–superconductor–normal metal trilayers
Scientific Reports
title Upper critical fields in normal metal–superconductor–normal metal trilayers
title_full Upper critical fields in normal metal–superconductor–normal metal trilayers
title_fullStr Upper critical fields in normal metal–superconductor–normal metal trilayers
title_full_unstemmed Upper critical fields in normal metal–superconductor–normal metal trilayers
title_short Upper critical fields in normal metal–superconductor–normal metal trilayers
title_sort upper critical fields in normal metal superconductor normal metal trilayers
url https://doi.org/10.1038/s41598-025-98332-1
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