Interface superconductivity in FeSe on SrTiO 3 thin films grown by the PLD technique

In this study, we fabricate 7–25-nm-thick films of FeSe/STO using pulsed laser deposition (PLD). The grown films exhibit superconductivity with an onset Tc that is much higher than that of bulk FeSe under ambient pressure. The observed Tc values are exceptionally high in terms of the strain vs. Tc relationship of the same material established so far. Furthermore, Tc increases as the film thickness decreases. This is in good agreement with the results reported for films grown by molecular beam epitaxy (MBE) that exhibit interface superconductivity. These results indicate the realization of interface superconductivity in PLD-grown FeSe/STO. Furthermore, our PLD technique requires no post-annealing to realize interface superconductivity, which is different from MBE techniques. Because the PLD technique has the advantage that various interfaces can be fabricated easily by simply altering the target materials, our results open novel routes to study interface superconductivity toward higher Tc by systematic control of the interface.