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HL: Fachverband Halbleiterphysik

HL 4: Complex Oxides: Bulk Properties (jointly with DS, HL, KFM, MA, O) (joint session TT/HL/MA)

HL 4.9: Vortrag

Montag, 16. März 2020, 11:45–12:00, HSZ 201

Charge transport in oxygen-deficient EuTiO₃: The emerging picture of dilute metallicity in quantum-paraelectric perovskite oxides — •Johannes Engelmayer¹, Xiao Lin¹, Christoph Grams¹, Raphael German¹, Tobias Fröhlich¹, Joachim Hemberger¹, Kamran Behnia², and Thomas Lorenz¹ — ¹II. Physikalisches Institut, Universität zu Köln, Germany — ²Laboratoire Physique et Etude de Matériaux, PSL Research University, 75005 Paris, France

Quantum paraelectric SrTiO₃ is a large-gap band insulator that becomes metallic upon electron doping already at extremely small charge-carrier concentrations ≃ 5× 10¹⁷cm⁻³. The observed T² resistivity in this material challenges conventional theories for electron–electron scattering. We report on a study of charge transport in the related compound EuTiO₃ where the carrier density is tuned via reduction. Because of a lower electric permittivity, the metal–insulator transition (MIT) in EuTiO_3−δ occurs at higher carrier densities compared to doped SrTiO₃. The critical carrier concentration n_c for the MIT is discussed in the context of the so-called Mott criterion and compared with other doped perovskite compounds with a quantum-paraelectric parent. Similar to doped SrTiO₃, EuTiO_3−δ shows a distinct AT² resistivity, where the prefactor A scales with n. Using a simple three-band model, the A(n) behavior in doped perovskite titanates can be described over a large range of n.
Funded by DFG via CRC1238 and via ANR-DFG LO 818/6-1 and HE 3219/6-1.