[Seminar] Hybridization and interaction between quantum multipolar fluctuations in a conventional magnet

Speaker

Dr. Martin Mourigal - Georgia Institute of Technology, Atlanta, USA

Title

Hybridization and interaction between quantum multipolar fluctuations in a conventional magnet

Abstract

One of the scientific frontiers in quantum magnetism is the discovery and understanding of quantum entangled and topologically ordered states in real bulk materials. At the focal point of the experimental investigation of these quantum spin networks is the identification of fractionalized excitations in transport and spectroscopic measurements. Inelastic neutron scattering has proved a powerful technique to reveal such signatures in a variety of systems ranging from quasi-1D magnets to kagome compounds and more. Recent and on-going developments with neutron scattering instrumentation have allowed the characterization of magnetic excitations in entire volumes of momentum-energy space with high resolution. This has prompted revisiting long overlooked materials in search for exotic spin dynamics despite seemingly classical magnetically ordered ground-states. In this talk, I will discuss such experiments on a long-known material, FeI2, and show how high-fidelity modeling brings new insights on its spin dynamics [1]. I will describe the mechanism that endows low energy quadrupolar fluctuations in FeI2 with large spectral weight and how these can be completely understood using a SU(3) representation of spin degrees of freedom. I will discuss the consequence of the having several quasiparticles as the low-energy degrees of freedom in this system [2]. This work was supported by DOE/BES under award DE-SC-0018660. 

[1] X. Bai, S.-S. Zhang, Z. L. Dun, H. Zhang, Q. Huang, H. D. Zhou, M. B. Stone, A. I. Kolesnikov, F. Ye, C. D. Batista, M. Mourigal, “Hybridized quadrupolar excitations in the frustrated and spin-anisotropic magnet FeI2 ”, Nature Physics (January 2021), https://doi.org/10.1038/s41567-020-01110-1, https://arxiv.org/abs/2004.05623.

[2] A. Legros, S.-S. Zhang, X. Bai, H. Zhang, Z. L. Dun, W. A. Phelan, C. D. Batista, M. Mourigal, and N. P. Armitage, “Observation of 4- and 6-magnon bound-states in the spin-anisotropic frustrated antiferromagnet FeI2”, Submitted (November 2020), https://arxiv.org/abs/2012.04205.

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