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arXiv · 2204.14209

Site-specific electronic and magnetic excitations of the skyrmion material Cu$_2$OSeO$_3$

Yanhong Gu·Yilin Wang·Jiaqi Lin·Jonathan Pelliciari·Jiemin Li·Myung-Geun Han·Marcus Peter Schmidt·Gabriel Kotliar·Claudio Mazzoli·Mark P. M. Dean·Valentina Bisogni
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Abstract

The manifestation of skyrmions in the Mott-insulator Cu$_2$OSeO$_3$ originates from a delicate balance between magnetic and electronic energy scales. As a result of these intertwined couplings, the two symmetry-inequivalent magnetic ions, Cu-I and Cu-II, bond into a spin S=1 entangled tetrahedron. However, conceptualizing the unconventional properties of this material and the energy of the competing interactions is a challenging task due the complexity of this system. Here we combine X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering to uncover the electronic and magnetic excitations of Cu$_2$OSeO$_3$ with site-specificity. We quantify the energies of the 3d crystal-field splitting for both Cu-I and Cu-II, fundamental to optimize model Hamiltonians. Additionally, we unveil a site-specific magnetic mode, indicating that individual spin character is preserved within the entangled-tetrahedron picture. Our results thus provide experimental constraint for validating theories that describe the interactions of Cu$_2$OSeO$_3$, highlighting the site-selective capabilities of resonant spectroscopies

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Yanhong Gu, Yilin Wang, Jiaqi Lin, Jonathan Pelliciari, Jiemin Li, Myung-Geun Han, Marcus Peter Schmidt, Gabriel Kotliar, Claudio Mazzoli, Mark P. M. Dean, Valentina Bisogni. 2022-04-29. Site-specific electronic and magnetic excitations of the skyrmion material Cu$_2$OSeO$_3$. https://doi.org/10.1038/s42005-022-00934-y

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