Coupled spin-lattice fluctuations in a compound with orbital degrees of freedom: the Cr based dimer system Sr3Cr2O8

Abstract

We report on an extended fluctuation regime in the spin dimer system Sr3Cr2O8 based on anomalies in Raman active phonons and magnetic scattering. The compound has two characteristic temperatures, TS = 275 K, related to a Jahn-Teller transition with structural distortions and orbital ordering and a second, T*= 150 K, which is due to further changes in the orbital sector. Below TS quasielastic scattering marks strong fluctuations and in addition phonon anomalies are observed. For temperatures below T* we observe an exponential decrease of one phonon linewidth and determine a gap of the orbital excitations. At low temperatures the observation of two- and three-magnon scattering allows the determination of the spin excitation gap.

7 pages, 4 figures, 1 table

References in corpus (2)

• Dynamical Dzyaloshinsky-Moriya Interaction in KCuF3
• Ordered moment in the anisotropic and frustrated square lattice Heisenberg model

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• ESR evidence for partial melting of the orbital order in LaMnO${}_3$ below the Jahn-Teller transition
• Neutron diffraction of field-induced magnon condensation in the spin-dimerized antiferromagnet Sr${}_3$Cr${}_2$O${}_8$
• Tuning the orbital-lattice fluctuations in the mixed spin-dimer system Ba${}_{3-x}$Sr${}_x$Cr${}_2$O${}_8$