High-pressure study of topological semimetals XCd2Sb2 (X = Eu and Yb) |
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Affiliation: | 1.State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200438, China;2.School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China;3.Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China;4.Shanghai Research Center for Quantum Sciences, Shanghai 201315, China |
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Abstract: | Topological materials have aroused great interest in recent years, especially when magnetism is involved. Pressure can effectively tune the topological states and possibly induce superconductivity. Here we report the high-pressure study of topological semimetals $X$Cd$_{2}$Sb$_{2}$ ($X = {rm Eu} $ and Yb), which have the same crystal structure. In antiferromagnetic (AFM) Weyl semimetal EuCd$_{2}$Sb$_{2}$, the Néel temperature (${T}_{rm N}$) increases from 7.4 K at ambient pressure to 50.9 K at 14.9 GPa. When pressure is above 14.9 GPa, the AFM peak of resistance disappears, indicating a non-magnetic state. In paramagnetic Dirac semimetal candidate YbCd$_{2}$Sb$_{2}$, pressure-induced superconductivity appears at 1.94 GPa, then ${ T}_{rm c}$ reaches to a maximum of 1.67 K at 5.22 GPa and drops to zero at about 30 GPa, displaying a dome-shaped temperature-pressure phase diagram. High-pressure x-ray diffraction measurement demonstrates that a crystalline-to-amorphous phase transition occurs at about 16 GPa in YbCd$_{2}$Sb$_{2}$, revealing the robustness of pressure-induced superconductivity against structural instability. Similar structural phase transition may also occur in EuCd$_{2}$Sb$_{2}$, causing the disappearance of magnetism. Our results show that $X$Cd$_{2}$Sb$_{2}$ ($X = {rm Eu}$ and Yb) is a novel platform for exploring the interplay among magnetism, topology, and superconductivity. |
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Keywords: | high pressure topological semimetal magnetism superconductivity |
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