2020/04/08 by Y. Ihara, K. Arashima, H. Yoshida +2 · 1 citation
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevresearch.2.023269
published as Phys. Rev. Research 2, 023269 (2020) · 5 pages, 5 figures
arxiv created 2020/04/08 · arxiv updated 2020/07/01
We present a 35Cl NMR study for spin S=1/2 perfect kagome antiferromagnet Ca-kapellasite (CaCu3(OH)6Cl2⋅0.6H2O) with a magnetic transition at T∗=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.