Structural and magnetic properties of Fe/ZnSe(001) interfaces

TL;DR

This study uses first principles calculations to analyze the structural and magnetic properties of Fe/ZnSe(001) interfaces, revealing how termination, reconstruction, and layer thickness influence magnetic moments and surface segregation.

Contribution

It provides detailed insights into the atomic and magnetic structure of Fe/ZnSe interfaces, including effects of surface reconstruction and growth direction, which were previously not comprehensively understood.

Findings

Se segregates at the surface, consistent with experiments.

Fe magnetic moments at the interface are higher than bulk Fe.

Reconstruction affects Fe bonding and interface properties.

Abstract

We have performed first principles electronic structure calculations to investigate the structural and magnetic properties of Fe/ZnSe(001) interfaces. Calculations involving full geometry optimizations have been carried out for a broad range of thickness of Fe layers(0.5 monolayer to 10 monolayers) on top of a ZnSe(001) substrate. Both Zn and Se terminated interfaces have been explored. Total energy calculations show that Se segregates at the surface which is in agreement with recent experiments. For both Zn and Se terminations, the interface Fe magnetic moments are higher than the bulk bcc Fe moment. We have also investigated the effect of adding Fe atoms on top of a reconstructed ZnSe surface to explore the role of reconstruction of semiconductor surfaces in determining properties of metal-semiconductor interfaces. Fe breaks the Se dimer bond formed for a Se-rich (2x1) reconstructed surface. Finally, we looked at the reverse growth i.e. growth of Zn and Se atoms on a bcc Fe(001) substrate to investigate the properties of the second interface of a magnetotunnel junction. The results are in good agreement with the theoretical and experimental results, wherever available.