Dresden 2017 – scientific programme

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PV: Plenarvorträge

PV XX

PV XX: Prize Talk

Thursday, March 23, 2017, 13:15–13:45, HSZ 01

Exotic Spin-Orbital Order in Transition Metal Oxides — •Andrzej M. Oles — Marian Smoluchowski Institute of Physics, Jagiellonian University, prof. S. Łojasiewicza 11, Krakow, Poland — Max Planck Institute for Solid State Research, Stuttgart, Germany — Laureate of the Smoluchowski-Warburg-Prize

Strong Coulomb interactions in transition metal oxides suppress charge fluctuations and lead to spin-orbital entanglement in superexchange which has numerous consequences for magnetic and optical properties of Mott insulators [1]. Here we consider: (i) nematic order in the 2D compass model at finite temperature [2]; (ii) entanglement spectra controlling quantum phase transitions [3]; (iii) charge defects in doped Y_1−xCa_xVO₃ with robust spin-orbital order and soft kinetic gap within the defect band [4]; (iv) orbital dilution for d³ (Mn⁴⁺, Cr³⁺) impurities in (Ca,Sr)₂RuO₄, and (v) charge dilution due to hole-doublon pairs for d² doping. We show that orbital dilution (iv) modifies locally or even globally spin-orbital order [5]. For charge dilution (v) intersite excitations on the d⁴-d² hybrid bonds generate T_i⁺T_j⁺ terms responsible for enhanced quantum fluctuations. Our findings are expected to be of importance for future experimental and theoretical studies of correlated Mott insulators with impurities.

We thank for support by NCN Project No. 2012/04/A/ST3/00331.

[1] A. M. Oleś, J. Phys.: Condensed Matter 24, 313201 (2012).

[2] P. Czarnik et al., Phys. Rev. B 93, 184410 (2016).

[3] W.-L. You et al., New J. Phys. 17, 083009 (2015).

[4] A. Avella et al., Phys. Rev. Lett. 115, 206403 (2015).

[5] W. Brzezicki et al., Phys. Rev. X 5, 011037 (2015).