Chern insulating phases and thermoelectric properties of EuO/MgO(001) superlattices

The topological and thermoelectric properties of ( Eu O )n / ( Mg O )m (001) superlattices (SLs) are explored using density functional theory calculations including a Hubbard U term together with Boltzmann transport theory. In ( Eu O )1 / ( Mg O )3 (001) SL at the lattice constant of MgO a sizable b...

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Bibliographic Details
Published in:Physical review. B 2021-01, Vol.103 (4), p.1, Article 045135
Main Authors: Köksal, Okan, Pentcheva, Rossitza
Format: Article
Language:English
Subjects:
Density functional theory
Energy gap
Ferromagnetism
Lattice parameters
Magnesium oxide
Mathematical analysis
Properties (attributes)
Seebeck effect
Spin-orbit interactions
Superlattices
Thermoelectricity
Topology
Transport theory
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Summary:The topological and thermoelectric properties of ( Eu O )n / ( Mg O )m (001) superlattices (SLs) are explored using density functional theory calculations including a Hubbard U term together with Boltzmann transport theory. In ( Eu O )1 / ( Mg O )3 (001) SL at the lattice constant of MgO a sizable band gap of 0.51 eV is opened by spin-orbit coupling (SOC) due to a band inversion between occupied localized Eu 4 f and empty 5 d conduction states. This inversion between bands of opposite parity is accompanied by a reorientation in the spin texture along the contour of band inversion surrounding the Γ point and leads to a Chern insulator with C = –1, also confirmed by the single edge state. Moreover, this Chern insulating phase shows promising thermoelectric properties, e.g., a Seebeck coefficient between 400 and 800 μ VK−1. A similar SOC-induced band inversion takes place also in the ferromagnetic semimetallic ( Eu O )2 / ( Mg O )2 (001) SL. Despite the vanishing band gap, it leads to a substantial anomalous Hall conductivity with values up to –1.04 e2 / h and somewhat lower Seebeck coefficient. Both cases emphasize the relation between nontrivial topological bands and thermoelectricity also in systems with broken inversion symmetry.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.103.045135