Lattice and electronic states of thin FeSe films on ${\mathrm{LaAlO}}_3$ substrates are investigated in the vicinity of the nematic phase transition. No evidence of a structural phase transition is found by x-ray diffraction below $T^{*}\sim 90$ K, while results obtained from a resistivity measurement and angle-resolved photoemission spectroscopy clearly show the appearance of a nematic state. These results indicate the formation of a pure nematic state in the iron-based superconductor and provide conclusive evidence that the nematic state originates from the electronic degrees of freedom. This pure nematicity in the thin film implies the difference in the electron-lattice interaction from bulk FeSe crystals. FeSe films provide valuable playgrounds for observing the pure response of “bare” electron systems free from the electron-lattice interaction, and should make an important contribution to investigate nematicity and its relationship with superconductivity.

Close

PrevNext

View figure in article

• Nematic order
• Superconductivity
• Iron-based superconductors
• Thin films
• Angle-resolved photoemission spectroscopy
• X-ray diffraction