Glassy freezing of orbital dynamics in FeCr2S4 and FeSc2S4

Abstract

We report on a thorough dielectric investigation of the glass-like freezing of the orbital reorientation-dynamics, recently found for the crystalline sulpho-spinels FeCr2S4 and FeSc2S4. As the orbital reorientations are coupled to a rearrangement of the surrounding ionic lattice via the Jahn-Teller effect, the freezing of the orbital moments is revealed by a relaxational behaviour of the complex dielectric permittivity. Additional conductivity (both dc and ac) and contact contributions showing up in the spectra are taken into account by an equivalent circuit description. The orbital relaxation dynamics continuously slows down over six decades in time, before at the lowest temperatures the glass transition becomes suppressed by quantum tunnelling.

arXiv commentJ. Non-Cryst. Solids, in press. 6 pages, 4 figures

References in corpus (3)

• Materials with Colossal Dielectric Constant: Do They Exist?
• Spin and orbital frustration in MnSc_2S_4 and FeSc_2S_4
• Orbital Freezing in FeCr2S4 Studied by Dielectric Spectroscopy

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• Designing Quantum Spin-Orbital Liquids in Artificial Mott Insulators