Optically induced metallic state with persistent monoclinic symmetry in NdNiO3
Abstract
Understanding whether electronic and structural order remain coupled under nonequilibrium conditions is a central challenge in correlated materials. Here, we simultaneously track metallicity and symmetry across the photoinduced insulator-to-metal transition in NdNiO3 using time-resolved optical reflectivity and symmetry-sensitive second-harmonic generation. We find that metallic reflectivity emerges at significantly lower excitation fluence than restoration of the orthorhombic high-temperature symmetry. As a result, optical excitation stabilizes a metastable state that combines the reflectivity of the metallic phase with the monoclinic symmetry of the insulating phase, revealing an optically induced monoclinic metal. Only at substantially higher fluences does the symmetry fully recover to that of the high-temperature phase. These results demonstrate a nonequilibrium decoupling of metallicity and structural symmetry and establish simultaneous multiprobe spectroscopy as a powerful approach for identifying emergent phases in correlated materials.
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BibTeX
@misc{tzschaschel2026optically,
title = {{Optically induced metallic state with persistent monoclinic symmetry in NdNiO$_3$}},
author = {Christian Tzschaschel and Felix Utsch and Qi Song and Spencer Doyle and Grace A. Pan and Charles M. Brooks and Julia A. Mundy and Clemens von Korff Schmising and Stefan Eisebitt},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11238},
eprint = {2609.11238},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11238},
}
RIS
TY - UNPB
TI - Optically induced metallic state with persistent monoclinic symmetry in NdNiO_3
AU - Christian Tzschaschel
AU - Felix Utsch
AU - Qi Song
AU - Spencer Doyle
AU - Grace A. Pan
AU - Charles M. Brooks
AU - Julia A. Mundy
AU - Clemens von Korff Schmising
AU - Stefan Eisebitt
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.11238
UR - https://arxiv.org/abs/2609.11238
AB - Understanding whether electronic and structural order remain coupled under nonequilibrium conditions is a central challenge in correlated materials. Here, we simultaneously track metallicity and symmetry across the photoinduced insulator-to-metal transition in NdNiO_3 using time-resolved optical reflectivity and symmetry-sensitive second-harmonic generation. We find that metallic reflectivity emerges at significantly lower excitation fluence than restoration of the orthorhombic high-temperature symmetry. As a result, optical excitation stabilizes a metastable state that combines the reflectivity of the metallic phase with the monoclinic symmetry of the insulating phase, revealing an optically induced monoclinic metal. Only at substantially higher fluences does the symmetry fully recover to that of the high-temperature phase. These results demonstrate a nonequilibrium decoupling of metallicity and structural symmetry and establish simultaneous multiprobe spectroscopy as a powerful approach for identifying emergent phases in correlated materials.
ER -