Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 86: Ferroics and Multiferroics (joint session KFM/TT/MA)

TT 86.3: Talk

Thursday, March 15, 2018, 10:10–10:30, EMH 225

Superconductivity and ferroelectric quantum criticality in KTaO3 — •Tobias Esswein, Awadhesh Narayan, and Nicola Spaldin — Materials Theory, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland

Electron doped cubic perovskite KTaO3 has recently been shown to become superconducting [1]. In the closely related material SrTiO3, a ferroelectric quantum critical point was proposed to be the origin of superconductivity [2]. In this work, using first-principles calculations, we show that a ferroelectric quantum critical point emerges with electron doping in KTaO3, lying at doping values close to the top of the superconducting dome. We examine the effects of larger spin-orbit coupling and absence of crystal field splitting in KTaO3, in comparison to SrTiO3, on the phonon spectrum, electron-phonon coupling and quantum oscillations. Our findings contribute to the growing understanding of superconductivity around quantum critical points and could help in designing materials with higher superconducting critical temperatures.

[1] Ueno, K. et al. Discovery of Superconductivity in KTaO3 by Electrostatic Carrier Doping. Nature Nanotechnology 6, 408 (2011). [2] Edge, J. M., Kedem, Y., Aschauer, U., Spaldin, N. A. & Balatsky, A. V. Quantum Critical Origin of the Superconducting Dome in SrTiO3. Physical Review Letters 115, 247002 (2015).