Quadrupolar magnetic excitations in an isotropic spin-1 antiferromagnet

Abstract

The microscopic origins of emergent behaviours in condensed matter systems are encoded in their excitations. In ordinary magnetic materials, single spin-flips give rise to collective dipolar magnetic excitations called magnons. Likewise, multiple spin-flips can give rise to multipolar magnetic excitations in magnetic materials with spin $\mathbf{S}\ge 1$. Unfortunately, since most experimental probes are governed by dipolar selection rules, collective multipolar excitations have generally remained elusive. For instance, only dipolar magnetic excitations have been observed in isotropic $\mathbf{S}=1$ Haldane spin systems. Here, we unveil a hidden quadrupolar constituent of the spin dynamics in antiferromagnetic $\mathbf{S}=1$ Haldane chain material Y${}_2$BaNiO${}_5$ using Ni ${\mathbf{L}}_3$-edge resonant inelastic x-ray scattering. Our results demonstrate that pure quadrupolar magnetic excitations can be probed without direct interactions with dipolar excitations or anisotropic perturbations. Originating from on-site double spin-flip processes, the quadrupolar magnetic excitations in Y${}_2$BaNiO${}_5$ show a remarkable dual nature of collective dispersion. While one component propagates as non-interacting entities, the other behaves as a bound quadrupolar magnetic wave. This result highlights the rich and largely unexplored physics of higher-order magnetic excitations.

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Cited by in corpus (14)

• Exploring Quantum Materials with Resonant Inelastic X-Ray Scattering
• Topological Hybrids of Magnons and Magnon Bound Pairs
• Unraveling higher-order corrections in the spin dynamics of RIXS spectra
• Eight-color chiral spin liquid in the $S=1$ bilinear-biquadratic model with Kitaev interactions
• Novel magnetic excitations beyond the single- and double-magnons
• Single- and Multimagnon Dynamics in Antiferromagnetic $\alpha$-Fe${}_2$O${}_3$ Thin Films
• Gravitational wave analogues in spin nematics and cold atoms
• Transition to the Haldane phase driven by electron-electron correlations
• Spin-1 Haldane chains of superconductor-semiconductor hybrids
• Revealing Quadrupolar Excitations with Non-Linear Spectroscopy
• Resonant inelastic x-ray scattering spectra of spinon, doublon, and quarton excitations of a spin-$\frac{1}{2}$ antiferromagnetic Heisenberg trimer chain
• Haldane phases and phase diagrams of the S = 3/2, 1 bilinear-biquadratic Heisenberg model on the orthogonal dimer chain
• The spin-one Duffin-Kemmer-Petiau equation revisited: analytical study of its structure and a careful choice of interaction
• Instability of the Haldane Phase: Roles of Charge Fluctuations and Hund's Coupling