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arXiv · 2511.07747

Optical spectroscopy of single- and two-ion transitions in an antiferromagnetic stoichiometric rare-earth crystal

Masaya Hiraishi·Gabrielle A. Hunter-Smith·Gavin G. G. King·Alexandra A. Turrini·J. -R. Soh·Henrik M. Rønnow·Luke S. Trainor·Jevon J. Longdell
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Abstract

We characterise optical transitions of neodymium ions (Nd3+) in antiferromagnetic neodymium gallate (NdGaO3) with applied fields up to 3 T. The magnetic phase of this material has not previously been studied with the field along its magnetisation axis. The measured optical spectra indicate three magnetic phases -- antiferromagnetic, intermediate, and paramagnetic -- where the intermediate phase likely forms a different magnetic structure from typical spin-flop phases. The observed absorptions were classified into two distinct families of optical transitions: single-Nd and two-Nd absorptions. We demonstrate that the optical transitions in the antiferromagnetic and paramagnetic phases can be modelled using a standard single-ion crystal-field Hamiltonian that interacts with a mean magnetisation from the rest of the lattice, and we expand that model to encompass pairs of ions, explaining the origins of the two-Nd transitions. This study offers a deeper understanding of the optical transitions in rare-earth antiferromagnetic crystals, which have been recently attracting significant interest for microwave-to-optical quantum transduction, despite being relatively unexplored to date.

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Masaya Hiraishi, Gabrielle A. Hunter-Smith, Gavin G. G. King, Alexandra A. Turrini, J. -R. Soh, Henrik M. Rønnow, Luke S. Trainor, Jevon J. Longdell. 2025-11-11. Optical spectroscopy of single- and two-ion transitions in an antiferromagnetic stoichiometric rare-earth crystal. https://arxiv.org/abs/2511.07747

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