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arXiv · 2005.13920

Unconventional critical behaviors at the magnetic phase transition of Co3Sn2S2 kagome ferromagnet

Mohamed A. Kassem·Yoshikazu Tabata·Takeshi Waki·Hiroyuki Nakamura
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Abstract

Co3Sn2S2 has generated a growing interest as a rare example of the highly uniaxial anisotropic kagome ferromagnet showing a combination of frustrated-lattice magnetism and topology. Recently, via precise measurements of the magnetization and AC susceptibility we have found a low-field anomalous magnetic phase (A-phase) with very slow spin dynamics that appears just below the Curie temperature (T_C). The A-phase hosts high-density domain bubbles after cooling through T_C as revealed in a previous in-situ Lorentz-TEM study. Here, we present further signatures of the anomalous magnetic transition (MT) at T_C revealed by a study of the critical behaviors of the magnetization and magnetocaloric effect using a high-quality single crystal. Analyses of numerous magnetization isotherms around T_C (177 K) using different approaches (the modified Arrot plot, Kouvel-Fisher method and magnetocaloric effect) result in consistent critical exponents that do not satisfy the theoretical predictions of standard second-order-MT models. Scaling analyses for the magnetization, magnetic entropy change and field-exponent of the magnetic entropy change, all consistently show low-field deviations below TC from the universal curves. Our results reveal that the MT of Co3Sn2S2 can not be explained as a conventional second-order type and suggest an anomalous magnetic state below T_C.

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Mohamed A. Kassem, Yoshikazu Tabata, Takeshi Waki, Hiroyuki Nakamura. 2020-05-28. Unconventional critical behaviors at the magnetic phase transition of Co3Sn2S2 kagome ferromagnet. https://doi.org/10.1088/1361-648x/abaf94

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