Impact of strain-induced electronic topological transition on the thermoelectric properties ofPtCoO2andPdCoO2

Abstract

By a combination of first-principles calculations and semi-classical Boltzmann transport theory, we investigate the effect of epitaxial strain on the electronic structure and transport properties of PtCoO2 and PdCoO2. In contrast to the rather uniform elastic response of both systems, we predict for PtCoO2 a high sensitivity of the out-of-plane transport properties to strain, which is not present in PdCoO2. At ambient temperature, we identify a considerable absolute change in the thermopower from −107 µV/K at −5 % compressive strain to −303 µV/K at +5 % tensile strain. This remarkable response is related to distinct changes of the Fermi surface, which involve the crossing of two additional bands at a moderate compressive in-plane strain. Combining our transport results with available experimental data on electrical and lattice thermal conductivity we predict a thermoelectric figure of merit of up to ZT = 0.25 at T = 600 K for strained PtCoO2.

High Thermopower with Metallic Conductivity in p-Type Li-Substituted PbPdO2

“…3 k-points (ie. 29791 k-points) in the full Brillouin zone which, in combination with the standard settings for BOLTZTRAP, provided sufficiently converged transport properties in the prior, similar case of PtCoO 2 48. Starting approximately from U ef f = U − J = 3 eV, a band gap opens that is significantly smaller than the gap obtained with the hybrid functional as seen in Figure6(b).…”

The properties of ultrapure delafossite metals

“…subsequently observed in experiments on single crystals [52]. Interesting calculations of phonon frequencies and strain--dependent physical properties have also been reported [24,54]. Table 2 Summary of key metallic parameters for PdCoO2.…”

Inducing n - and p -Type Thermoelectricity in Oxide Superlattices by Strain Tuning of Orbital-Selective Transport Resonances

“…1,2 Considerable experimental and computational 3 research aims at finding oxide thermoelectrics with improved performance, mostly among bulk materials by doping [4][5][6][7] or strain. 8 An alternative strategy is to exploit heterostructuring and dimensional confinement. [9][10][11][12][13][14][15][16] This is promoted by the advancement of growth techniques that allow to design transition metal oxide superlattices (SLs) with atomic precision.…”