Seminarium "Coherence-Correlations-Complexity" (KFT, PWr)

13:15 Wednesday, 02-12-20
Platforma Zoom

Are spins and orbitals entangled in the Mott insulators with large spin-orbit coupling?

dr hab. Krzysztof Wohlfeld

Institute of Theoretical Physics of the University of Warsaw

The seminar will be broadcast on the Zoom platform (the link will be made available to interested persons after prior contact at ).


The Mott insulating iridium oxides have recently attracted a lot of attention: while some of them are strikingly similar to the "high-Tc" cuprates, the others are described by the Kitaev-Heisenberg models and are good candidate materials to observe the "proximate spin-liquid" phases. One of the main reasons for the onset of such intriguing physics is the relatively large value of the spin-orbit coupling on the iridium ions, which is widely believed to lead to the so-called *spin-orbital entanglement*. Interestingly, however, the relation between the spin-orbital entanglement and the spin-orbit coupling is rather speculative.

In this talk, after a brief overview of the above-mentioned "iridate physics", I will discuss how the spin-orbital entanglement can be induced in a Mott insulator with large spin-orbit coupling [1]. In particular, I will show that: (i) the spin-orbital entanglement between spins and orbitals on different sites can be triggered by a joint action of the on-site spin-orbit coupling (of relativistic origin) and the spin-orbitalexchange (of the Kugel-Khomskii type); and yet, (ii) the onset of the spin-orbital entanglement in such a model does not have to  be  taken  for  granted,  for  it  can  vanish  even  in  the  large spin-orbit coupling limit.

[1] D. Gotfryd et al., Phys. Rev. Research 2, 013353 (2020).

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