Spin Screening and Antiscreening in a Ferromagnet/Superconductor Heterojunction

TL;DR

This paper theoretically investigates how a superconductor can screen or antiscreen the magnetic moment of an adjacent ferromagnet, depending on electron polarization at the Fermi level, with proposed experiments to verify these effects.

Contribution

It introduces a theoretical framework explaining spin screening and antiscreening in ferromagnet/superconductor heterojunctions based on electron polarization.

Findings

Magnetic moment can be screened or antiscreened depending on electron polarization.

Proposes experimental verification using ferromagnetic alloys with specific Fe or Ni concentrations.

Discusses effects of different density of states configurations.

Abstract

We present a theoretical study of spin screening effects in a ferromagnet/superconductor (F/S) heterojunction. It is shown that the magnetic moment of the ferromagnet is screened or antiscreened, depending on the polarization of the electrons at the Fermi level. If the polarization is determined by the electrons of the majority (minority) spin band then the magnetic moment of the ferromagnet is screened (antiscreened) by the electrons in the superconductor. We propose experiments that may confirm our theory: for ferromagnetic alloys with certain concentration of Fe or Ni ions there will be screening or antiscreening respectively. Different configurations for the density of states are also discussed.