Unconventional critical behaviors at the magnetic phase transition of Co3Sn2S2 kagomé ferromagnet. (13th October 2020)

• Record Type: Journal Article
• Authors: Kassem, Mohamed A; Tabata, Yoshikazu; Waki, Takeshi; Nakamura, Hiroyuki
• Is Part Of: Journal of physics. Volume 33:Number 1(2021)
• Publication Date: 2020-10-13
• Subjects: Kagome ferromagnet -- frustrated magnetism -- critical behavior -- magnetocaloric effect -- ferromagnetic anomaly -- anomalous magnetic transition; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/abaf94
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Co3 Sn2 S2 has generated a growing interest as a rare example of the highly uniaxial anisotropic kagomé 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 T C from the universal curves. Our results reveal that the MT of Co3 Sn2 S2 can not be explained as a conventional second-order type and suggest an anomalous magnetic state below T C .