Effects of substrate-surface reconstruction and orientation on spin-valley polarization in MoTe$_2$/EuO

TL;DR

This study examines how substrate surface reconstruction and orientation influence spin-valley polarization in MoTe$_2$ monolayers on EuO, revealing that interface details significantly affect valley polarization strength.

Contribution

It provides first-principles insights into how surface reconstruction and orientation of EuO substrates modulate spin-valley polarization in MoTe$_2$, highlighting the importance of interface structure.

Findings

Valley polarization varies from a few meV to 40 meV depending on interface details.

Reconstructed EuO(111) shows weaker valley polarization compared to ideal EuO(111).

EuO(001) induces a stable valley polarization of about 3.2 meV.

Abstract

We investigate the spin-valley polarization in MoTe$_2$ monolayer on (111) and (001) surfaces of ferromagnetic semiconductor EuO based on first-principles calculations. We consider surface reconstructions for EuO(111). We find that there is no direct chemical bonding between the reconstructed EuO(111) and the MoTe$_2$ overlayer, in contrast to the case of the ideal EuO(111). However, there is a strong hybridization between the states of MoTe$_2$ and the substrate states, which has a substantial impact on the valleys. The valley polarization due to the magnetic proximity effect is dependent on the detail of the interface structure, which is in the range of a few meV to about 40 meV. These values are at least one order of magnitude smaller than that induced by the ideal EuO(111). When the MoTe$_2$ monolayer is interfaced with EuO(001), the valley polarization is about 3.2 meV, insensitive to the interface structure. By a low-energy effective Hamiltonian model, the effective Zeeman field induced by EuO(001) is about 27 T, comparable to that for WSe$_2$/EuS obtained by experiment.