%A Zhaohui Cheng(程朝晖), Bin Lei(雷彬), Xigang Luo(罗习刚), Jianjun Ying(应剑俊), Zhenyu Wang(王震宇), Tao Wu(吴涛), and Xianhui Chen(陈仙辉) %T Revealing the A1g-type strain effect on superconductivity and nematicity in FeSe thin flake %0 Journal Article %D 2021 %J Chin. Phys. B %R 10.1088/1674-1056/ac1efa %P 97403-097403 %V 30 %N 9 %U {https://cpb.iphy.ac.cn/CN/abstract/article_123884.shtml} %8 2021-08-19 %X The driving mechanism of nematicity and its twist with superconductivity in iron-based superconductors are still under debate. Recently, a dominant B1g-type strain effect on superconductivity is observed in underdoped iron-pnictides superconductors Ba(Fe1-xCox)2As2, suggesting a strong interplay between nematicity and superconductivity. Since the long-range spin order is absent in FeSe superconductor, whether a similar strain effect could be also observed or not is an interesting question. Here, by utilizing a flexible film as substrate, we successfully achieve a wide-range-strain tuning of FeSe thin flake, in which both the tensile and compressive strain could reach up to ~0.7%, and systematically study the strain effect on both superconducting and nematic transition (Tc and Ts) in the FeSe thin flake. Our results reveal a predominant A1g-type strain effect on Tc. Meanwhile, Ts exhibits a monotonic anti-correlation with Tc and the maximum Tc reaches to 12 K when Ts is strongly suppressed under the maximum compressive strain. Finally, in comparison with the results in the underdoped Ba(Fe1-xCox)2As2, the absence of B1g-type strain effect in FeSe further supports the role of stripe-type spin fluctuations on superconductivity. In addition, our work also supports that the orbital degree of freedom plays a key role to drive the nematic transition in FeSe.