From one- to two-magnon excitations in the S=3/2 magnet $\beta$-CaCr${}_2$O${}_4$

Abstract

We apply neutron spectroscopy to measure the magnetic dynamics in the S=3/2 magnet $\beta$-CaCr${}_2$O${}_4$ (T${}_N$=21 K). The low-energy fluctuations, in the ordered state, resemble large-S linear spin-waves from the incommensurate ground state. However, at higher energy transfers, these semi-classical and harmonic dynamics are replaced by an energy and momentum broadened continuum of excitations. Applying kinematic constraints required for energy and momentum conservation, sum rules of neutron scattering, and comparison against exact diagonalization calculations, we show that the dynamics at high-energy transfers resemble low-S one-dimensional quantum fluctuations. $\beta$-CaCr${}_2$O${}_4$ represents an example of a magnet at the border between classical Néel and quantum phases, displaying dual characteristics.

References in corpus (5)

• Magnon Decay in Noncollinear Quantum Antiferromagnets
• Non-collinear spin-density wave antiferromagnetism in FeAs
• Soft striped magnetic fluctuations competing with superconductivity in Fe_{1+x}Te
• Decay of spin-spin correlations in disordered quantum and classical spin chains
• Imitation of spin density wave order in Cu${}_3$Nb${}_2$O${}_8$

Cited by in corpus (8)

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• Strain-induced phase diagram of the $S=\frac{3}{2}$ Kitaev material $\mathrm{CrSiT}{\mathrm{e}}_3$
• Kernel Polynomial Method for Linear Spin Wave Theory
• Excitonic transverse and amplitude fluctuations in the noncollinear and charge-ordered RbFe${}^{2+}$Fe${}^{3+}$F${}_6$
• Neutron scattering sum rules, symmetric exchanges, and helicoidal magnetism in MnSb${}_2$O${}_6$
• Spin and lattice dynamics of a van der Waals antiferromagnet MnPSe${}_3$
• Single-ion anisotropy driven chiral magnetic order in a spin-1 antiferromagnetic chain