Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 19: Poster Session: Correlated Electrons 1

TT 19.52: Poster

Monday, March 20, 2017, 15:00–19:00, P2-EG

Impact of electron doping on thermodynamic and transport properties of the magnetoelectric antiferromagnet EuTiO_3−δ — •Johannes Engelmayer, Christoph Grams, Xiao Lin, Joachim Hemberger, and Thomas Lorenz — II. Physikalisches Institut, Universität zu Köln, Germany

Various perovskite titanates ATiO₃ are known to undergo ferroelectric phase transitions, e.g., for A=Ba,Pb,Cd. In contrast, CaTiO₃ and SrTiO₃ show quantum paraelectric behavior, that is, ferroelectric long-range order is suppressed by quantum fluctuations. In addition, the insulating SrTiO₃ becomes metallic upon electron doping via oxygen deficiencies (SrTiO_3−δ with δ > 0) and even shows superconductivity for certain carrier concentrations. The rare-earth titanate EuTiO₃ is similar to SrTiO₃. Both, Eu²⁺ and Sr²⁺ have the same ionic radii, but Sr²⁺ is nonmagnetic while Eu²⁺ has a large magnetic moment of 7µ_B. Below T_N=5.5 K the localized 4f moments order antiferromagnetically in a G-type configuration. While stoichiometric EuTiO₃ is semiconducting, metallic behavior can be induced by oxygen deficiencies, similar to SrTiO_3−δ. Here, we present a detailed characterization of EuTiO_3−δ with −10⁻²≤δ≤ 10⁻² based on field- and temperature-dependent measurements of magnetization, specific heat, and thermal expansion. Moreover we use resistivity and permittivity measurements as complementary methods to investigate the magnetoelectric properties, since the conductivity of the samples covers 17 orders of magnitude.