High temperature superconducting FeSe films on SrTiO3 substrates

Area of Science:

• Condensed matter physics
• Materials science
• Superconductivity

Background:

• Interface superconductivity in two-dimensional materials is a key research area.
• Iron selenide (FeSe) is a promising material for studying superconductivity at the nanoscale.

Purpose of the Study:

• To investigate the superconducting properties of one-unit-cell (1-UC) FeSe films.
• To compare the behavior of 1-UC FeSe grown on conductive (Nb-STO) and insulating (STO) substrates.

Main Methods:

• Growth of ultra-thin FeSe films with one unit cell thickness.
• Magnetization versus temperature (M-T) measurements.
• Transport measurements, including sheet resistance and Hall resistance.

Main Results:

• 1-UC FeSe on Nb-STO shows a magnetization drop crossover around 85 K.
• FeSe films on insulating STO exhibit Arrhenius TAFF behavior in sheet resistance.
• Sign reversal of Hall resistance indicates a crossover from hole to electron conduction above the critical temperature (TC).

Conclusions:

• Substrate choice significantly impacts the superconducting properties of 1-UC FeSe films.
• The observed phenomena highlight complex electronic behavior in ultra-thin superconductors.
• 1-UC FeSe films present a unique platform for exploring fundamental physics of superconductivity.