Superconductivity and magnetism in FeSe thin films grown by metal–organic chemical vapor deposition

Abstract

High quality FeSe thin films with different ratios of Fe to Se have been grown on GaAs and Si substrates by changing the flow rate of Fe(CO)5 in a low-pressure metal–organic chemical vapor deposition (MOCVD) system. For both substrates, the films grown at a low flow rate of Fe(CO)5 are non-ferromagnetic and exhibit superconductivity at low temperature, while those grown at a high flow rate of Fe(CO)5 display ferromagnetic and semiconducting behaviors. Our results suggest that the superconducting phase does exist in a narrow range of Fe and Se concentration near stoichiometry. The introduction of excess Fe favors ferromagnetism and leads to the suppression of superconductivity.

Superconductivity in Fe-chalcogenides

“…Thin films were synthesized with other approaches such as metal-organic chemical vapor deposition (MOCVD) [29,30], molecular beam epitaxy (MBE) [31], and electrochemical synthesis [32]. In general it is found that β-FeSe 1-x Te x can be easily grown in a wide temperature range (250°C-600°C) on various substrates such as MgO, LaAlO 3 , SrTiO 3 , Si, SiO x /Si, GaAs, R-Al 2 O 3 , CaF2, and LSAT.…”

Recent advances in β-FeSe1−x and related superconductors

“…FeSe 1− x Te x (FST) thin films can be prepared by many methods, such as pulsed laser deposition (PLD) [4, 40–42], molecular beam epitaxy (MBE) [43, 44] and metalorganic chemical vapor deposition (MOCVD) [45]. Various substrates are used for growing epitaxial FST thin films, including SrTiO 3 , MgO, YAlO 3 , LaAlO 3 (LAO), Si, GaAs and r-Al 2 O 3 , despite some of them having a large lattice mismatch with FeSe 1− x Te x .…”

Superconducting properties of iron chalcogenide thin films

“…• C, again for 12 h. There is very limited mention of superconducting films grown by other common techniques, such as molecular beam epitaxy [27,28], metalorganic chemical vapor deposition (MOCVD) [29] and sputtering [30]. Recently, very thick (thickness 100 µm) superconducting films of FeSe (T onset c = 8 K) were successfully deposited by electrochemical route [31].…”