TaSe2 has several different polytypes and abundant physical properties such as superconductivity and charge density waves (CDW), which had been investigated in the past few decades. However, there is no report on the physical properties of 4Ha polytype up to now. Here we report the crystal growth and discovery of superconductivity in the tantalum self-intercalated 4Ha-Ta1.03Se2 single crystal with a superconducting transition onset temperature Tc≈ 2.7 K, which is the first observation of superconductivity in 4Ha polytype of TaSe2. A slightly suppressed CDW transition is found around 106 K. A large μ0Hc2/Tc value of about 4.48 is found when magnetic field is applied in the ab plane, which probably results from the enhanced spin-orbit coupling(SOC). Special stacking faults are observed, which further enhance the anisotropy. Although the density of states at the Fermi level is lower than that of other polytypes, Tc remains the same, indicating the stack mode of 4Ha polytype may be beneficial to superconductivity in TaSe2.
@article{arxiv.1801.09371,
title = {Superconductivity in tantalum self-intercalated 4$Ha$-Ta$_{1.03}$Se$_2$},
author = {Hua Bai and Mengmeng Wang and Xiaohui Yang and Yupeng Li and Jiang Ma and Xikang Sun and Qian Tao and Linjun Li and Zhu-An Xu},
journal= {arXiv preprint arXiv:1801.09371},
year = {2018}
}