Large spin splittings due to the orbital degree of freedom and spin textures in a ferroelectric nitride perovskite

Hong Jian Zhao (1) , Peng Chen (1) , Charles Paillard (2) , Rémi Arras (3) , Yue-Wen Fang (4) , Xu Li (5) , Julien Gosteau (3) , Yurong Yang (5) , Laurent Bellaiche (1)

1 University of Arkansas [Fayetteville]
2 SPMS - Laboratoire Structures, Propriétés et Modélisation des solides
3 CEMES-MEM - Matériaux et dispositifs pour l'Electronique et le Magnétisme
4 Kyoto University
5 LSSMS - National Laboratory of Solid State Microstructures [Nanjing University]

First-principles simulations are conducted to predict that ferroelectric nitride perovskite LaWN 3 not only exhibits large spin splittings (2.7 eV Å) but also possesses unique spin textures for some of its conduction levels. Such spin splittings around the and L points cannot be interpreted as a typical mixture of Rashba or Dresselhaus configurations but rather require the development of four-band k • p models with high-order terms. We further identify that, for some bands, spin splittings can be greatly contributed by the pure orbital degree of freedom (PODF), a unique character of our four-band Hamiltonian compared to the traditional two-band version. The concept of PODF-enhanced spin splittings paves a way for designing materials with large spin splittings. Moreover, the energy levels possessing such large splittings and complex spin textures can be brought close to the conduction-band minimum by applying epitaxial strain.

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Physique Numérique [physics.comp-ph]; Chimie-Physique [physics.chem-ph]

Hong Jian Zhao, Peng Chen, Charles Paillard, Rémi Arras, Yue-Wen Fang, et al.. Large spin splittings due to the orbital degree of freedom and spin textures in a ferroelectric nitride perovskite. Physical Review B, 2020, 102 (4), pp.041203. ⟨10.1103/PhysRevB.102.041203⟩. ⟨hal-02988959⟩