High-temperature superconductivity in one-unit-cell FeSe films

Abstract

Since the dramatic enhancement of the superconducting transition temperature (T ) was reported in a one-unit-cell FeSe film grown on a SrTiO substrate (1-UC FeSe/STO) by molecular beam epitaxy (MBE), related research on this system has become a new frontier in condensed matter physics. In this paper, we present a brief review on this rapidly developing field, mainly focusing on the superconducting properties of 1-UC FeSe/STO. Experimental evidence for high-temperature superconductivity in 1-UC FeSe/STO, including direct evidence revealed by transport and diamagnetic measurements, as well as other evidence from scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES), are overviewed. The potential mechanisms of the enhanced superconductivity are also discussed. There are accumulating arguments to suggest that the strengthened Cooper pairing in 1-UC FeSe/STO originates from the interface effects, specifically the charge transfer and coupling to phonon modes in the TiO plane. The study of superconductivity in 1-UC FeSe/STO not only sheds new light on the mechanism of high-temperature superconductors with layered structures, but also provides an insight into the exploration of new superconductors by interface engineering.

Stabilization and heteroepitaxial growth of metastable tetragonal FeS thin films by pulsed laser deposition

“…As for carrier doping, we demonstrated that the T c of FeSe was raised to 35 K by extremely high-density electron accumulation using electric-double layer transistor (EDLT) structures [13,14]. This kind of carrier-induced high T c has also been reported in [15−18] and observed for monolayer-thick FeSe [9,19].…”

“…According to the above XRF result, we then tried to tune the [Fe]/[S] ratio to reach stoichiometry by adding excess S to the PLD bulk targets. The nominal compositions of PLD targets we examined were 9 FeS 1+x (x = 0, 0.1, 0.2, and 0.4). Other parameters were all fixed; i.e.…”

Linear correlation between the c-axis lattice constant and superconducting critical temperature in FeSe0.5Te0.5 thin films

“…The 11 type iron-based superconductor (FeSe 1−x Te x ) have drawn much attention in basic research and applications, especially in superconducting mechanism exploration [1,2], because of their simplest crystal structure and non-toxic properties [3,4]. The bulk FeSe showed a superconducting transition temperature (T c ) of about 8K [5], and the superconductivity onset in α-FeSe was reported to attain a broad maximum of 37 K under 7 GPa hydrostatic pressure [6].…”

Interface‐Driven Structural Distortions and Composition Segregation in Two‐Dimensional Heterostructures

“…[2,3] Fore xample,g raphene films have much larger carrier mobilities on hexagonal boron nitride substrates than on silicon oxide substrates. [8] Forl ayered heterostructures, the structures of rock salt-like 2D layers have also been found to vary systematically with thickness and also with the dichalcogenide constituent that they are layered with in heterostructures. [8] Forl ayered heterostructures, the structures of rock salt-like 2D layers have also been found to vary systematically with thickness and also with the dichalcogenide constituent that they are layered with in heterostructures.…”