Magnetization-dependent $T_c$ shift in F/S/F trilayers with a strong ferromagnet

TL;DR

This study investigates how the superconducting transition temperature in Ni/Nb/Ni trilayers varies with magnetization alignment, revealing a significant $T_c$ shift that highlights the potential of strong ferromagnets in superconductor heterostructures.

Contribution

It demonstrates a large magnetization-dependent $T_c$ shift in Ni/Nb/Ni trilayers, showing strong ferromagnets are promising for future superconductor-ferromagnet research.

Findings

$T_c$ difference up to 41 mK between P and AP states

Largest $T_c$ shift occurs near the critical Nb thickness

Strong ferromagnets show promise for heterostructure applications

Abstract

We have measured the superconducting transition temperature $T_c$ of Ni/Nb/Ni trilayers when the magnetizations of the two outer Ni layers are parallel (P) and antiparallel (AP). The largest difference in $T_c$ occurs when the Nb thickness is just above the critical thickness at which superconductivity disappears completely. We have observed a difference in $T_c$ between the P and AP states as large as 41 mK - a significant increase over earlier results in samples with higher $T_c$ and with a CuNi alloy in place of the Ni. Our result also demonstrates that strong elemental ferromagnets are promising candidates for future investigations of ferromagnet/superconductor heterostructures.