Electronic structure and nematic phase transition in superconducting multiple-layer FeSe films grown by pulsed laser deposition method

Shen Bing^{1, 2}, Feng Zhong-Pei^{1, 2}, Huang Jian-Wei^{1, 2}, Hu Yong^{1, 2}, Gao Qiang^{1, 2}, Li Cong^{1, 2}, Xu Yu^{1, 2}, Liu Guo-Dong¹, Yu Li¹, Zhao Lin^{1, †}, Jin Kui^{1, ‡}, Zhou X J^{1, 2, 3, §}

Fermi surface and band structure for the FeSe/CaF₂ films with a . (a) Resistivity measurement of the sample. The onset is about 4 K. (b1) and (b2) show Fermi surface mapping measured at a low temperature of 30 K and a high temperature of 210 K. They are obtained by integrating the spectral weight within a narrow energy window of [−20 meV, 10 meV] with respect to the Fermi level. (c1)–(c8) show band structure measured at different temperatures along the momentum cut that crosses the point. (d1)–(d8) and (e1)–(e8) show the results along the other two momentum cuts that cross M2 and M3 respectively. The locations of the three momentum cuts are marked by red lines in (b1). The second derivative images with respect to energy are presented here in order to show the band structure more clearly. The corresponding temperature is shown above these band images. The observed bands are labeled in (c1), (d1), and (e1).