Observation of three superconducting transitions in the pressurized CDW-bearing compound <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>TaTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>
Jing Guo, Cheng Huang, Huixia Luo, Huaixin Yang, Linlin Wei, Shu Cai, Yazhou Zhou, Hengcan Zhao, Xiaodong Li, Yanchun Li, Ke Yang, Aiguo Li, Peijie Sun, Jianqi Li, Qi Wu, R. J. Cava, Liling Sun
Abstract
Transition metal dichalcogenides host a wide variety of lattice and electronic structures, as well as corresponding exotic physical properties, especially under certain tuning conditions. Here, we report the observation of pressure-induced three superconducting transitions in ${\mathrm{TaTe}}_{2}$, a charge density wave (CDW)--bearing layered transition-metal dichalcogenide that is metallic but not superconducting at ambient pressure. We find that its CDW state can be easily suppressed upon increasing pressure up to \ensuremath{\sim}1 GPa. A superconducting state then emerges from the suppressed CDW state and persists to the pressure about 7 GPa. Unexpectedly, another superconducting state appears at \ensuremath{\sim}11 GPa within the same monoclinic (M) structure of its ambient-pressure one. Upon further compression to 21 GPa, a third superconducting state with higher ${T}_{c}$ appears from a high-pressure (HP) phase. Our experimental results suggest that the pressure-induced three superconducting transitions in ${\mathrm{TaTe}}_{2}$ are, respectively, driven by the suppression of the CDW state, the change of the \ensuremath{\beta} angle in the M phase and the transition of M-to-HP phase. These results demonstrate not only the versatile nature of this correlated electron system, but also the first experimental example that shows the pressure-induced evolution from a CDW state to three superconducting states driven by different mechanisms.