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arXiv · 2510.21622

Zeeman Spectroscopy of Vacancy-Charge-Compensated Er3+ Sites in CaWO4 under Vector Magnetic Fields

Fabian Becker·Sudip KC·Lorenz J. J. Sauerzopf·Tim Schneider·Luis Risinger·Christian Schmid·Kai Müller
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Abstract

We present polarization-resolved optical absorption measurements on Er3+ ions in CaWO4 under vector magnetic fields, focusing on charge-compensated sites arising from local Ca2+ vacancies. While the known axial Er3+ site displays a single symmetric Zeeman-split transition pattern consistent with S4 symmetry, two additional sites exhibit more complex spectral behavior, including sets of transitions that interchange under 90{\deg} crystal rotations-evidence of reduced, rhombic-like symmetry. From these polarization- and temperature-dependent spectra, we extract effective g-factors. Our findings are corroborated by electron paramagnetic resonance measurements and support a model of multiple inequivalent Ca2+ vacancies around Er3+ sites in the host lattice. This detailed characterization contributes to understanding defect-engineered rare-earth sites for quantum information applications.

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Fabian Becker, Sudip KC, Lorenz J. J. Sauerzopf, Tim Schneider, Luis Risinger, Christian Schmid, Kai Müller. 2025-10-24. Zeeman Spectroscopy of Vacancy-Charge-Compensated Er3+ Sites in CaWO4 under Vector Magnetic Fields. https://arxiv.org/abs/2510.21622

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