Elastic Instabilities within Antiferromagnetically Ordered Phase in the Orbitally-Frustrated Spinel GeCo${}_2$O${}_4$

Abstract

Ultrasound velocity measurements of the orbitally-frustrated GeCo${}_2$O${}_4$ reveal unusual elastic instabilities due to the phonon-spin coupling within the antiferromagnetic phase. Shear moduli exhibit anomalies arising from the coupling to short-range ferromagnetic excitations. Diplike anomalies in the magnetic-field dependence of elastic moduli reveal magnetic-field-induced orbital order-order transitions. These results strongly suggest the presence of geometrical orbital frustration which causes novel orbital phenomena within the antiferromagnetic phase.

5 pages, 3 figures

References in corpus (6)

• Orbital ordering and frustrations
• Molecular spin resonance in the geometrically frustrated MgCr2O4 magnet by inelastic neutron scattering
• Magnetic frustration in the spinel compounds Ge Co_2 O_4 and Ge Ni_2 O_4
• Doubly degenerate orbital system in honeycomb lattice: implication of orbital state in layered iron oxide
• Dilution Effects in Two-dimensional Quantum Orbital System
• Jahn-Teller Inactivity and Magnetic Frustration in GeCo${}_2$O${}_4$ Probed by Ultrasound Velocity Measurements

Cited by in corpus (14)

• Spin Insulatronics
• Hedgehog-lattice spin texture in classical Heisenberg antiferromagnets on the breathing pyrochlore lattice
• Observation of elastic anomalies driven by coexisting dynamical spin Jahn-Teller effect and dynamical molecular spin state in paramagnetic phase of the frustrated MgCr${}_2$O${}_4$$
• Berezinskii-Kosterlitz-Thouless Type Scenario in Molecular Spin Liquid $A$Cr${}_2$O${}_4$
• Acoustic study for dynamical molecular-spin state without undergoing magnetic phase transition in spin-frustrated ZnFe${}_2$O${}_4$
• Multiple lattice instabilities resolved by magnetic-field and disorder sensitivities in cubic paramagnetic phase of the orbital-degenerate frustrated spinel MgV${}_2$O${}_4$
• Field driven magnetostructural transitions in GeCo${}_2$O${}_4$
• Hedgehog lattice and field-induced chirality in breathing-pyrochlore Heisenberg antiferromagnets
• Orbital- and spin-driven lattice instabilities in quasi-one-dimensional CaV${}_2$O${}_4$
• A variety of elastic anomalies in orbital-active nearly-itinerant cobalt vanadate spinel
• Softening of breathing elastic mode and trigonal elastic mode in disordered pyrochlore magnet NaCaCo${}_2$F${}_7$
• Symmetry-resolved elastic anomalies in spin-crossover cobaltite LaCoO${}_3$
• High-field phase diagram of the chiral-lattice antiferromagnet Sr(TiO)Cu4(PO4)4
• Elastic softness of low-symmetry frustrated $A$Ti${}_2$O${}_5$ ($A$ = Co, Fe)