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MA: Fachverband Magnetismus

MA 18: Functional Antiferromagnetism

MA 18.2: Vortrag

Dienstag, 18. März 2025, 14:15–14:30, H19

Understanding the role of spin non-conserving on magnon excitation — •Hebatalla Elnaggar — Sorbonne University, Paris, France

Conventional wisdom suggests that one photon that carries one unit of angular momentum (1h) can change the spin angular momentum of a magnetic site with one unit (*M* = *1h) at most following the selection rules. This implies that a two-photon process such as 2*3* resonant inelastic X-ray scattering (RIXS) can change the spin angular momentum of a magnetic system with a maximum of two units (*M* = * 2h). Herein we describe a triple-magnon excitation in *-Fe2O3 and various perovskite thin films, which contradicts this conventional wisdom that only 1- and 2-magnon excitations are possible in a resonant inelastic X-ray scattering experiment [1].

We observe an excitation at exactly three times the magnon energy, along with additional excitations at four and five times the magnon energy, suggesting quadruple and quintuple magnons as well. Guided by theoretical calculations, we reveal how a two-photon scattering process can create exotic higher-rank magnons due to spin non-conserving interactions.

References: 1- H. Elnaggar, et. al., Magnetic excitations beyond the single- and double-magnons, Nat. Commun. 14, 2749 (2023).

Keywords: Magnons; Antiferromagnetic materials; Spin non-conserving interactions; Thin films