Speaker
Description
EuAuSb is a layered Dirac semimetal which exhibits a variety of unusual transport
phenomena, including chiral magnetic and topological Hall e?ects. The topological Hall
e?ect in particular is seen only in the magnetically ordered phase, suggesting that
symmetry breaking due to magnetic order may be important for understanding electronic
behavior. We have therefore collected single-crystal neutron di?raction measurements
and identified an incommensurate helical order in which ferromagnetic Eu2+ layers rotate
in-plane by ~120° from one layer to the next [1]. An in-plane magnetic field distorts the
incommensurate order, eventually leading to a first order transition to a commensurate
state, followed by the field polarized state. In the field range where topological Hall e?ect is
at a maximum, we observe a suppression of the in-plane ordered moment and consider
possible explanations for this observation. The observed magnetic order also breaks both
parity and time-reversal symmetries, leading to a loss of spin degeneracy in the band
structure even in the absence of spin-orbit coupling. We compare this spin-splitting to that
seen in the collinear altermagnets, as well as the more recently studied coplanar magnetic
materials termed p-wave or odd-wave magnets.
[1] J. Sears, Juntao Yao, Zhixiang Hu, Wei Tian, Niraj Aryal, Weiguo Yin, A. M. Tsvelik, I. A. Zaliznyak,
Qiang Li, and J. M. Tranquada, EuAuSb: A helical variation on altermagnetism, arXiv:2505.00081
(2025)
Work at Brookhaven is supported by the OWice of Basic Energy Sciences, Materials Sciences and
Engineering Division, U.S. Department of Energy (DOE) under Contract No. DE-SC0012704
| Topical Area | Hard matter: quantum, electronic, semiconducting materials |
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