Spin-orbital entangled molecular jeff states in lacunar spinel compounds

Heung-Sik Kim, Jino Im, Myung Joon Han, Hosub Jin
2014 Nature Communications  
The entanglement of the spin and orbital degrees of freedom through the spin-orbit coupling has been actively studied in condensed matter physics. In several iridium-oxide systems, the spin-orbital entangled state, identified by the effective angular momentum j_ eff, can host novel quantum phases with the help of electron correlations. Here, we show that a series of lacunar spinel compounds, GaM_4X_8 (M = Nb, Mo, Ta, and W and X = S, Se, and Te), gives rise to a molecular j_ eff state as a new
more » ... eff state as a new spin-orbital composite on which the low energy effective Hamiltonian is based. A wide range of electron correlations is accessible by tuning the bandwidth under external and/or chemical pressure, enabling us to investigate the interesting cooperation between spin-orbit coupling and electron correlations. As illustrative examples, a two-dimensional topological insulating phase and an anisotropic spin Hamiltonian are investigated in the weak and strong coupling regimes, respectively. Our finding can provide an ideal platform for exploring j_ eff physics and the resulting emergent phenomena.
doi:10.1038/ncomms4988 pmid:24889209 fatcat:xh4puuuukbf4bnljhpfcqp7qiu