Motivated by the discovery of superconductivity in KTaO3-based heterostructures, we study a pairing mechanism based on spin-orbit assisted coupling between the conduction electrons and the ferroelectric (FE) modes present in the material. We use ab initio frozen-phonon computations to show a linear-in-momentum Rashba-like coupling with a strong angular dependence in momentum for the lower j = 3 / 2 manifold, deviating from the conventional isotropic Rashba model. This implies the Rashba-like interaction with the polar modes has substantial L = 3 cubic harmonic corrections, which we quantify for each electronic band. The strong anisotropy of the Rashba interaction is captured by a microscopic toy model for the t 2 g electrons. We find its origin to be the angular dependence in electronic momentum imposed by the kinetic term on the degenerate j = 3 / 2 manifold. A comparison between the toy model and ab initio results indicates that additional symmetry allowed terms beyond odd-parity spin-conserving inter-orbital hopping processes are needed to describe the Rashba-like polar interaction between the electrons and the soft FE mode. © 2023 The Author(s). Published by IOP Publishing Ltd.
Anisotropic Rashba coupling to polar modes in KTaO3
Giulia Venditti;Paolo Barone;Jose Lorenzana;
2023-01-01
Abstract
Motivated by the discovery of superconductivity in KTaO3-based heterostructures, we study a pairing mechanism based on spin-orbit assisted coupling between the conduction electrons and the ferroelectric (FE) modes present in the material. We use ab initio frozen-phonon computations to show a linear-in-momentum Rashba-like coupling with a strong angular dependence in momentum for the lower j = 3 / 2 manifold, deviating from the conventional isotropic Rashba model. This implies the Rashba-like interaction with the polar modes has substantial L = 3 cubic harmonic corrections, which we quantify for each electronic band. The strong anisotropy of the Rashba interaction is captured by a microscopic toy model for the t 2 g electrons. We find its origin to be the angular dependence in electronic momentum imposed by the kinetic term on the degenerate j = 3 / 2 manifold. A comparison between the toy model and ab initio results indicates that additional symmetry allowed terms beyond odd-parity spin-conserving inter-orbital hopping processes are needed to describe the Rashba-like polar interaction between the electrons and the soft FE mode. © 2023 The Author(s). Published by IOP Publishing Ltd.File | Dimensione | Formato | |
---|---|---|---|
prod_477973-doc_196308.pdf
accesso aperto
Descrizione: Anisotropic Rashba coupling to polar modes in KTaO3
Tipologia:
Versione Editoriale (PDF)
Licenza:
Creative commons
Dimensione
1.35 MB
Formato
Adobe PDF
|
1.35 MB | Adobe PDF | Visualizza/Apri |
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.