EuAuSb: An odd-parity helical variation on altermagnetism
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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| _version_ | 1866917056075530240 |
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| author | Sears, J. Yao, Juntao Hu, Zhixiang Tian, Wei Aryal, Niraj Yin, Weiguo Tsvelik, A. M. Zaliznyak, I. A. Li, Qiang Tranquada, J. M. |
| author_facet | Sears, J. Yao, Juntao Hu, Zhixiang Tian, Wei Aryal, Niraj Yin, Weiguo Tsvelik, A. M. Zaliznyak, I. A. Li, Qiang Tranquada, J. M. |
| contents | EuAuSb is a triangular-lattice Dirac semimetal in which a topological Hall effect has been observed to develop in association with a magnetically-ordered phase. Our single-crystal neutron diffraction measurements have identified an incommensurate helical order in which individual ferromagnetic Eu$^{2+}$ layers rotate in-plane by $\sim$120$^{\circ}$ from one layer to the next. An in-plane magnetic field distorts the incommensurate order, eventually leading to a first order transition to a state that is approximately commensurate and that is continuously polarized as the bulk magnetization approaches saturation. From an analysis of the magnetic diffraction intensities versus field, we find evidence for a dip in the ordered in-plane moment at the same field where the topological Hall effect is a maximum, and we propose that this is due to field-induced quantum spin fluctuations. Our electronic structure calculations yield exchange constants compatible with the helical order and show that the bands near the Fermi level lose their spin degeneracy via a mechanism similar to that in the collinear altermagnets. We find that, unlike the even symmetry seen in the altermagnets, the spin-splitting in EuAuSb has odd-wave symmetry similar to that recently found in a number of coplanar magnetic materials. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_00081 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | EuAuSb: An odd-parity helical variation on altermagnetism Sears, J. Yao, Juntao Hu, Zhixiang Tian, Wei Aryal, Niraj Yin, Weiguo Tsvelik, A. M. Zaliznyak, I. A. Li, Qiang Tranquada, J. M. Strongly Correlated Electrons EuAuSb is a triangular-lattice Dirac semimetal in which a topological Hall effect has been observed to develop in association with a magnetically-ordered phase. Our single-crystal neutron diffraction measurements have identified an incommensurate helical order in which individual ferromagnetic Eu$^{2+}$ layers rotate in-plane by $\sim$120$^{\circ}$ from one layer to the next. An in-plane magnetic field distorts the incommensurate order, eventually leading to a first order transition to a state that is approximately commensurate and that is continuously polarized as the bulk magnetization approaches saturation. From an analysis of the magnetic diffraction intensities versus field, we find evidence for a dip in the ordered in-plane moment at the same field where the topological Hall effect is a maximum, and we propose that this is due to field-induced quantum spin fluctuations. Our electronic structure calculations yield exchange constants compatible with the helical order and show that the bands near the Fermi level lose their spin degeneracy via a mechanism similar to that in the collinear altermagnets. We find that, unlike the even symmetry seen in the altermagnets, the spin-splitting in EuAuSb has odd-wave symmetry similar to that recently found in a number of coplanar magnetic materials. |
| title | EuAuSb: An odd-parity helical variation on altermagnetism |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2505.00081 |