NMR study of supersolid phases in the triangular-lattice antiferromagnet Na2BaCo(PO4)2

Fuente: arXiv
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Main Authors: Xu, Xiaoyu, Wu, Zhanlong, Chen, Ying, Huang, Qing, Hu, Ze, Shi, Xinyu, Du, Kefan, Li, Shuo, Bian, Rui, Yu, Rong, Cui, Yi, Zhou, Haidong, Yu, Weiqiang
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Published: 2025
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author Xu, Xiaoyu
Wu, Zhanlong
Chen, Ying
Huang, Qing
Hu, Ze
Shi, Xinyu
Du, Kefan
Li, Shuo
Bian, Rui
Yu, Rong
Cui, Yi
Zhou, Haidong
Yu, Weiqiang
author_facet Xu, Xiaoyu
Wu, Zhanlong
Chen, Ying
Huang, Qing
Hu, Ze
Shi, Xinyu
Du, Kefan
Li, Shuo
Bian, Rui
Yu, Rong
Cui, Yi
Zhou, Haidong
Yu, Weiqiang
contents We report ultra-low-temperature $^{23}$Na NMR measurements on the Ising triangular lattice antiferromagnet Na$_2$BaCo(PO$_4$)$_2$, which precisely resolve the phase diagram under magnetic field applied along the crystalline $c$ axis. With increasing field, the NMR spectra resolve three ordered phases with distinct spin configurations: the Y, up-up-down (UUD), and V phases. The spin-lattice relaxation rate $1/T_1$ data demonstrate gapless excitations in the Y and V phases, strongly supporting their supersolid nature. However, the phase transitions from the UUD phase to the two supersolid phases exhibit dramatically different behaviors upon cooling. Prior to entering the Y phase, $1/T_1$ identifies a gapless regime within the UUD phase, suggesting a Berezinskii-Kosterlitz-Thouless phase above a second-order phase transition. In contrast, the coexistence of the UUD and V phases observed in our experiments provides direct evidence of a first-order phase transition between these phases.
format Preprint
id arxiv_https___arxiv_org_abs_2504_08570
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle NMR study of supersolid phases in the triangular-lattice antiferromagnet Na2BaCo(PO4)2
Xu, Xiaoyu
Wu, Zhanlong
Chen, Ying
Huang, Qing
Hu, Ze
Shi, Xinyu
Du, Kefan
Li, Shuo
Bian, Rui
Yu, Rong
Cui, Yi
Zhou, Haidong
Yu, Weiqiang
Strongly Correlated Electrons
We report ultra-low-temperature $^{23}$Na NMR measurements on the Ising triangular lattice antiferromagnet Na$_2$BaCo(PO$_4$)$_2$, which precisely resolve the phase diagram under magnetic field applied along the crystalline $c$ axis. With increasing field, the NMR spectra resolve three ordered phases with distinct spin configurations: the Y, up-up-down (UUD), and V phases. The spin-lattice relaxation rate $1/T_1$ data demonstrate gapless excitations in the Y and V phases, strongly supporting their supersolid nature. However, the phase transitions from the UUD phase to the two supersolid phases exhibit dramatically different behaviors upon cooling. Prior to entering the Y phase, $1/T_1$ identifies a gapless regime within the UUD phase, suggesting a Berezinskii-Kosterlitz-Thouless phase above a second-order phase transition. In contrast, the coexistence of the UUD and V phases observed in our experiments provides direct evidence of a first-order phase transition between these phases.
title NMR study of supersolid phases in the triangular-lattice antiferromagnet Na2BaCo(PO4)2
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2504.08570