Magnetic field dependence of excitations near spin-orbital quantum criticality

Abstract

The spinel FeSc${}_2$S${}_4$ has been proposed to realize a near-critical spin-orbital singlet (SOS) state, where entangled spin and orbital moments fluctuate in a global singlet state on the verge of spin and orbital order. Here we report powder inelastic neutron scattering measurements that observe the full bandwidth of magnetic excitations and we find that spin-orbital triplon excitations of an SOS state can capture well key aspects of the spectrum in both zero and applied magnetic fields up to 8.5 T. The observed shift of low-energy spectral weight to higher energies upon increasing applied field is naturally explained by the entangled spin-orbital character of the magnetic states, a behavior that is in strong contrast to spin-only singlet ground state systems, where the spin gap decreases upon increasing applied field.

13 pages, 8 figures. Revised version now matches published manuscript

References in corpus (7)

• Quantum Magnets under Pressure: Controlling Elementary Excitations in TlCuCl3
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Cited by in corpus (7)

• Spin order and dynamics in the diamond-lattice Heisenberg antiferromagnets CuRh2O4 and CoRh2O4
• Field Driven Quantum Criticality in the Spinel Magnet ZnCr${}_2$Se${}_4$
• Emergent quantum criticality from spin-orbital entanglement in $d^8$ Mott insulators: the case of a diamond lattice antiferromagnet
• Magnetic order and exchange couplings in the frustrated diamond lattice antiferromagnet MnSc${}_2$Se${}_4$
• Structure, magnetic susceptibility and specific heat of the spin-orbital-liquid candidate FeSc2S4 : Influence of fe off-stoichiometry
• Electronic structure of the frustrated diamond lattice magnet NiRh${}_2$O${}_4$
• Frustrated $J_1-J_2$ Diamond Lattice Antiferromagnet Co${}_2$Ti${}_3$O${}_8$ with a Vacancy-ordered Spinel Structure Synthesized via a Topochemical Reaction