Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 101: Correlated Electrons: Other Materials

TT 101.3: Vortrag

Donnerstag, 15. März 2018, 16:00–16:15, HFT-FT 101

Thermodynamics and transport properties of oxygen-deficient EuTiO₃ — •Johannes Engelmayer¹, Christoph Grams¹, Xiao Lin¹, Kamran Behnia^1,2, Joachim Hemberger¹, and Thomas Lorenz¹ — ¹II. Physikalisches Institut, Universität zu Köln, Germany — ²Laboratoire Physique et Etude de Matériaux, PSL Research University, 75005 Paris, France

Various perovskite titanates ATiO₃ are known to undergo ferroelectric phase transitions, e.g., for A=Ba,Pb,Cd. In contrast, SrTiO₃ shows quantum paraelectric behavior, that is, ferroelectric long-range order is suppressed by quantum fluctuations. A partial substitution of Sr with Ca (Sr_1−xCa_xTiO₃) induces ferroelectricity. On the other hand, the insulating SrTiO₃ becomes metallic upon electron doping via oxygen deficiencies (SrTiO_3−δ) and furthermore shows superconductivity for certain carrier concentrations. If both—Ca and electron doping—is combined (Sr_1−xCa_xTiO_3−δ), even a coexistence of ferroelectricity and superconductivity seems to be possible [1]. EuTiO₃ is a promising candidate for comparable phenomena, since Eu²⁺ and Sr²⁺ have the same ionic radii, which results in identical structural characteristics. However, Eu²⁺ has a large magnetic moment of 7µ_B, in contrast to nonmagnetic Sr²⁺. Here, we present a detailed investigation of EuTiO_3−δ with |δ|≤ 10⁻² based on thermodynamic and transport measurements.
C. W. Rischau et al., Nat. Phys. 13, 643 (2017)