Low temperature enhancement of ferromagnetic Kitaev correlations in α-RuCl3

Abstract

Kitaev-type interactions between neighbouring magnetic moments emerge in the honeycomb material $\alpha$-RuCl3. It is debated however whether these Kitaev interactions are ferromagnetic or antiferromagnetic. With electron energy loss spectroscopy (EELS) we study the lowest excitation across the Mott-Hubbard gap, which involves a d4 triplet in the final state and therefore is sensitive to nearest-neighbor spin-spin correlations. At low temperature the spectral weight of these triplets is strongly enhanced, in accordance with optical data. We show that the magnetic correlation function that determines this EELS spectral weight is directly related to a Kitaev-type spin-spin correlator and that the temperature dependence agrees very well with the results of a microscopic magnetic Hamiltonian for $\alpha$-RuCl3 with ferromagnetic Kitaev coupling.

5 pages, 3 figures

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Cited by in corpus (7)

• Competing Antiferromagnetic-Ferromagnetic States in $d^7$ Kitaev Honeycomb Magnet
• Multiple Spin-Orbit Excitons and the Electronic Structure of $\alpha$-RuCl${}_3$
• Exchange interactions in $d^5$ Kitaev materials: From Na${}_2$IrO${}_3$ to $\alpha$-RuCl${}_3$
• Tunneling spectroscopic signatures of charge doping and associated Mott transition in $\alpha$-RuCl${}_3$ in proximity to graphite
• Spin-orbit coupling and crystal-field splitting in Ti-doped Ca2RuO4 studied by ellipsometry
• Non-local features of the spin-orbit exciton in Kitaev materials
• Nesting instability of gapless U(1) spin liquids with spinon Fermi pockets in two dimensions