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arXiv · 2004.03827

Anisotropic magnetic excitations from single-chirality antiferromagnetic state in Ca-kapellasite

Y. Ihara·K. Arashima·H. Yoshida·M. Hirata·T. Sasaki
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Abstract

We present a $^{35}$Cl NMR study for spin $S=1/2$ perfect kagome antiferromagnet Ca-kapellasite (CaCu$_{3}$(OH)$_{6}$Cl$_{2}\cdot$0.6H$_{2}$O) with a magnetic transition at $T^{\ast}=7.2$ K. The static magnetic structure in the ground state has been determined to be a chirality-ordered $Q=0$ state, which is selected by a finite Dzyaloshinskii-Moriya interaction. The low-energy magnetic excitations in the ordered state are investigated by the nuclear spin-lattice relaxation rate measurement. We detect a weakly temperature dependent contribution in the magnetic fluctuations perpendicular to the kagome plane in addition to the dispersive spin-wave contribution in the kagome plane. The low-energy magnetic excitations from the coplanar spin structure are attributed to the zero mode originating from the flat band in this kagome antiferromagnet.

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Y. Ihara, K. Arashima, H. Yoshida, M. Hirata, T. Sasaki. 2020-04-08. Anisotropic magnetic excitations from single-chirality antiferromagnetic state in Ca-kapellasite. https://doi.org/10.1103/physrevresearch.2.023269

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