Berlin 2015 – scientific programme
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MA: Fachverband Magnetismus
MA 22: Multiferroics I (DF with DS/KR/MA/TT)
MA 22.6: Talk
Wednesday, March 18, 2015, 10:45–11:00, EB 107
Tuning order-by-disorder multiferroicity in CuO by doping — •Johan Hellsvik1,2, Marcello Balestieri1, Tomoyasu Usui3, Alessandro Stroppa2, Anders Bergman4, Lars Bergqvist5, Dharmalingam Prabhakaran6, Olle Eriksson4, Silvia Picozzi2, Tsuyoshi Kimura3, and José Lorenzana1,2 — 1ISC-CNR, Rome, Italy — 2CNR-SPIN, L'Aquila, Italy — 3Osaka University, Osaka, Japan — 4Uppsala University, Uppsala, Sweden — 5KTH, Stockholm, Sweden — 6University of Oxford, Oxford, United Kingdom
The high Curie temperature multiferroic compound CuO has a quasidegenerate magnetic ground state that makes it prone to manipulation by the so-called "order-by-disorder" mechanism. First principle computations supplemented with Monte Carlo simulations and experiments show that isovalent doping allows us to stabilize the multiferroic phase in nonferroelectric regions of the pristine material phase diagram with experiments reaching a 250% widening of the ferroelectric temperature window with 5% of Zn doping. Our results allow us to validate the importance of a quasidegenerate ground state on promoting multiferroicity on CuO at high temperatures and open a path to the material engineering of multiferroic materials. In addition we present a complete explanation of the CuO phase diagram and a computation on the incommensurability in excellent agreement with experiment without free parameters.
[1] J. Hellsvik et al., Phys. Rev. B 90, 014437 (2014) [2] T. Kimura et al., Nature Mat. 7, 291 (2008) [3] G. Giovannetti et al., Phys. Rev. Lett. 106, 026401 (2011)