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arXiv · 1501.04022

Entanglement Driven Phase Transitions in Spin-Orbital Models

Wen-Long You·Andrzej M. Oleś·Peter Horsch
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Abstract

To demonstrate the role played by the von Neumann entropy spectra in quantum phase transitions we investigate the one-dimensional anisotropic SU(2)$\otimes XXZ$ spin-orbital model with negative exchange parameter. In the case of classical Ising orbital interactions we discover an unexpected novel phase with Majumdar-Ghosh-like spin-singlet dimer correlations triggered by spin-orbital entanglement and having $k=\pi/2$ orbital correlations, while all the other phases are disentangled. For anisotropic $XXZ$ orbital interactions both spin-orbital entanglement and spin-dimer correlations extend to the antiferro-spin/alternating-orbital phase. This quantum phase provides a unique example of two coupled order parameters which change the character of the phase transition from first-order to continuous. Hereby we have established the von Neumann entropy spectral function as a valuable tool to identify the change of ground state degeneracies and of the spin-orbital entanglement of elementary excitations in quantum phase transitions.

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Wen-Long You, Andrzej M. Oleś, Peter Horsch. 2015-01-16. Entanglement Driven Phase Transitions in Spin-Orbital Models. https://doi.org/10.1088/1367-2630/17/8/083009

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