Zollner, Klaus and Faria, Paulo E. Junior and Fabian, Jaroslav (2020) Giant proximity exchange and valley splitting in transition metal dichalcogenide/hBN/(Co, Ni) heterostructures. PHYSICAL REVIEW B, 101 (8): 085112. ISSN 2469-9950, 2469-9969
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We investigate the proximity-induced exchange coupling in transition-metal dichalcogenides (TMDCs), originating from spin injector geometries composed of hexagonal boron-nitride (hBN) and ferromagnetic (FM) cobalt (Co) or nickel (Ni), from first principles. We employ a minimal tight-binding Hamiltonian that captures the low energy bands of the TMDCs around K and K' valleys, to extract orbital, spin-orbit, and exchange parameters. The TMDC/hBN/FM heterostructure calculations show that due to the hBN buffer layer, the band structure of the TMDC is preserved, with an additional proximity-induced exchange splitting in the bands. We extract proximity exchange parameters in the 1-10 meV range, depending on the FM. The combination of proximity-induced exchange and intrinsic spin-orbit coupling (SOC) of the TMDCs, leads to a valley polarization, translating into magnetic exchange fields of tens of Tesla. The extracted parameters are useful for subsequent exciton calculations of TMDCs in the presence of a hBN/FM spin injector. Our calculated absorption spectra show large splittings for the exciton peaks; in the case of MoS2/hBN/Co we find a value of about 8 meV, corresponding to about 50 T external magnetic field in bare TMDCs. The reason lies in the band structure, where a hybridization with Co d orbitals causes a giant valence band exchange splitting of more than 10 meV. Structures with Ni do not show any d level hybridization features, but still sizable proximity exchange and exciton peak splittings of around 2 meV are present in the TMDCs.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | MOLYBDENUM-DISULFIDE; ELECTRONIC-STRUCTURE; MONOLAYER MOTE2; SPIN INJECTION; GRAPHENE; CONTACT; MOS2; POLARIZATION; LAYER; BN; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Theroretical Physics > Chair Professor Richter > Group Jaroslav Fabian |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 30 Mar 2021 12:06 |
| Last Modified: | 30 Mar 2021 12:06 |
| URI: | https://pred.uni-regensburg.de/id/eprint/45132 |
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