Effect of confinement and octahedral rotations on the electronic, magnetic, and thermoelectric properties of Sr<i>X</i>O₃/SrTiO₃(001) superlattices, (<i>X</i> = V, Cr, and Mn)

Transition metal oxides are an attractive class of materials for thermoelectric applications due to their chemical and thermal stability and environmental friendliness. Here we explore the effect of confinement and octahedral rotations on the electronic and thermoelectric properties of (SrXO₃)₁/(SrTiO₃)_n(001) (X = V, Cr, and Mn; n = 1, 3) superlattices by combining ab-initio simulations including an on-site Coulomb repulsion term and Boltzmann theory. We find that in the ground state, the superlattices always display finite octahedral rotations, which drive an orbital reconstruction and metal-to-insulator transition in SrVO₃ and SrCrO₃ single layers with ferro- and antiferromagnetic spin order, respectively. On the other hand, SrMnO₃ based superlattices exhibit antiferromagnetic spin order along with bulk-like properties. We show that tuning the quantum confinement plays an important role in improving the thermoelectric performance in these superlattices and the estimated electronic power factors compare favorably with some of the best performing transition metal oxide thermoelectrics.

[1] M. Verma, B. Geisler, and R. Pentcheva, Phys. Rev. B 100, 165126 (2019).