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Topological Hall effect induced by chiral fluctuations in a kagome lattice



Kyle Fruhling, Alenna Streeter, Sougata Mardanya, Xiaoping Wang, Priya Baral, Oksana Zaharko, Igor Mazin, Sugata Chowdhury, William Ratcliff, Fazel Tafti


Topological Hall effect (THE) is a hallmark of scalar spin chirality, which is found in static skyrmion lattices. Recent theoretical works have shown that scalar spin chirality could also emerge dynamically from thermal spin fluctuations. Evidence of such a mechanism was found in the kagome magnet YMn6Sn6 where fluctuations arise from frustrated exchange interactions between Mn kagome layers. In YMn6Sn6, the rare-earth ion Y3+ is non-magnetic. When it is replaced by a magnetic ion (Gd3+–Ho3+), the intrinsically antiferromagnetic Mn-Mn interlayer coupling is overwhelmed by the indirect ferromagnetic Mn-R-Mn one, relieving frustration. This generates interesting anomalous Hall conductivity, but not THE. Here we show that Er lies in an intermediate regime where direct and indirect interactions closely compete, so that ErMn6Sn6 can switch from one regime to the other by temperature, i.e., from a collinear ferrimagnetic ground state to a spiral antiferromagnet at 78 K. The AFM phase forms a dome in the temperature-field phase diagram. Close to the boundary of this dome, we find a sizable fluctuations-driven THE, thus underscoring the universality of this mechanism for generating non-zero scalar spin chirality
Science Advances


neutron, magnetism, topological


Fruhling, K. , Streeter, A. , Mardanya, S. , Wang, X. , Baral, P. , Zaharko, O. , Mazin, I. , Chowdhury, S. , Ratcliff, W. and Tafti, F. (2024), Topological Hall effect induced by chiral fluctuations in a kagome lattice, Science Advances (Accessed April 23, 2024)
Created January 30, 2024, Updated February 15, 2024