Magnetic proximity effect in superconductor/ferromagnet van der Waals heterostructures: dependence on the number of superconducting monolayers

TL;DR

This study explores how the magnetic proximity effect in van der Waals superconductor/ferromagnet heterostructures varies with the number of superconducting monolayers, revealing unique behaviors distinct from classical models.

Contribution

It demonstrates that the superconducting properties and spin splitting in ultrathin heterostructures depend on the number of layers and can be tuned by gating, challenging classical assumptions.

Findings

Superconducting order parameter shows dips related to the number of monolayers.

Large exchange fields do not necessarily suppress superconductivity.

Spin splitting manifests as multiple peaks, not a simple Zeeman effect.

Abstract

The magnetic proximity effect in superconductor/ferromagnet (S/F) heterostructures with a large number of atomic layers leads to a suppression of the superconducting order parameter and appearance of Zeeman-like spin splitting of the local density of states (LDOS). Here we study the magnetic proximity effects in van der Waals S/F heterostructures with a few atomic layers and demonstrate that the corresponding physics is very different from the classical results. We find that the dependence of the superconducting order parameter exhibits dips as a function of the ferromagnetic exchange field and gating. The number of dips is determined by the number of monolayers in the heterostructure and, in general, the superconductivity is not suppressed by large values of the exchange field. The spin splitting of the LDOS cannot be described by an effective Zeeman field and manifests a multiple peak structure, where each peak is connected to a unique spin splitting of one of the superconducting bands, which also can be tuned by gating.