Superconductivity in the Layered Cage Compound Ba$_{3}$Rh$_{4}$Ge$_{16}$
Yi Zhao1,2, Jun Deng3, A. Bhattacharyya4*, D. T. Adroja5,6, P. K. Biswas5, Lingling Gao1, Weizheng Cao1, Changhua Li1, Cuiying Pei1, Tianping Ying3,7, Hideo Hosono7, and Yanpeng Qi1*
1School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China 2University of Chinese Academy of Science, Beijing 100049, China 3Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China 4Department of Physics, Ramakrishna Mission Vivekananda Educational and Research Institute, Belur Math, Howrah 711202, West Bengal, India 5ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot Oxon, OX11 0QX, United Kingdom 6Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa 7Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
Abstract：We report the synthesis and superconducting properties of a layered cage compound Ba$_{3}$Rh$_{4}$Ge$_{16}$. Similar to Ba$_{3}$Ir$_{4}$Ge$_{16}$, the compound is composed of 2D networks of cage units, formed by noncubic Rh–Ge building blocks, in marked contrast to the reported rattling compounds. The electrical resistivity, magnetization, specific heat capacity, and μSR measurements unveiled moderately coupled s-wave superconductivity with a critical temperature $T_{\rm c}=7.0$ K, the upper critical field $\mu_{0}H_{\rm c2}(0) \sim 2.5$ T, the electron-phonon coupling strength $\lambda_{\rm e-ph} \sim 0.80$, and the Ginzburg–Landau parameter $\kappa \sim 7.89$. The mass reduction with the substitution of Ir by Rh is believed to be responsible for the enhancement of $T_{\rm c}$ and coupling between the cage and guest atoms. Our results highlight the importance of atomic weight of framework in cage compounds in controlling the $\lambda_{\rm e-ph}$ strength and $T_{\rm c}$.
. [J]. 中国物理快报, 2021, 38(12): 127402-.
Yi Zhao, Jun Deng, A. Bhattacharyya, D. T. Adroja, P. K. Biswas, Lingling Gao, Weizheng Cao, Changhua Li, Cuiying Pei, Tianping Ying, Hideo Hosono, and Yanpeng Qi. Superconductivity in the Layered Cage Compound Ba$_{3}$Rh$_{4}$Ge$_{16}$. Chin. Phys. Lett., 2021, 38(12): 127402-.
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