Incommensurate Magnetic Order in Sm$_3$BWO$_9$ with Distorted Kagome Lattice
Kai-Yue Zeng1,2, Fang-Yuan Song3, Lang-Sheng Ling1, Wei Tong1, Shi-Liang Li4,5, Zhao-Ming Tian3*, Long Ma1*, and Li Pi1,2
1Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China 2Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China 3School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China 4Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China 5School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
Abstract：We investigate the magnetic ground state of Sm$_3$BWO$_9$ with a distorted kagome lattice. A magnetic phase transition is identified at $T_{\rm N}=0.75$ K from the temperature dependence of specific heat. From $^{11}$B nuclear magnetic resonance measurements, an incommensurate magnetic order is shown by the double-horn type spectra under a $c$-axis magnetic field, and absence of line splitting is observed for field oriented within the $ab$-plane, indicating the incommensurate modulation of the internal field strictly along $c$-axis. From the spin dynamics, the critical slowing-down behavior is observed in the temperature dependence of $1/T_1$ with $\mu_0H$$\perp$$c$-axis, which is completely absent in the case with $\mu_0H||c$-axis. Based on the local symmetry of $^{11}$B sites, we analyze the hyperfine coupling tensors and propose two constraints on the possible magnetic structure. The single ion anisotropy should play an important role in determination of contrasting ground states of Sm$_3$BWO$_9$ and Pr$_3$BWO$_9$.
2022, Vol. 39 
