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TT: Fachverband Tiefe Temperaturen

TT 54: Fe-based Superconductors

TT 54.12: Vortrag

Donnerstag, 19. März 2020, 12:30–12:45, HSZ 201

MBE preparation and in-situ characterization of FeTe thin films — •Vanda M. Pereira¹, Chi-Nan Wu^{1, 2}, Cheng-En Liu^{1, 3}, Sheng-Chieh Liao¹, Chun-Fu Chang¹, Chang-Yang Kuo^{1, 4}, Cevriye Koz¹, Ulrich Schwarz¹, Hong-Ji Lin⁴, Chien-Te Chen⁴, Liu Hao Tjeng¹, and Simone G. Altendorf¹ — ¹MPI-CPfS, Dresden, Germany — ²Dept. of Physics, NTHU, Hsinchu, Taiwan — ³Dept. of Electrophysics, NCTU, Hsinchu, Taiwan — ⁴NSRRC, Hsinchu, Taiwan

Within the family of Fe based superconductors, Fe chalcogenides have received particular attention due to their simple crystal structure. Fe_1+yTe, which is not superconducting, has been studied extensively in bulk form and, more recently, some efforts have been made regarding the synthesis of thin films, resorting to pulsed laser deposition and molecular beam epitaxy (MBE). Here we report the results of Fe_1+yTe thin films grown by MBE under Te-limited growth conditions. We found that epitaxial layer-by-layer growth is possible for a wide range of excess Fe values, wider than expected from studies on the bulk material. Using XMCD at the Fe L_2,3 and Te M_4,5 edges, we observed that films with high excess Fe contain ferromagnetic clusters while films with lower excess Fe remain nonmagnetic. Moreover, x-ray absorption spectroscopy showed that it is possible to obtain films with very similar electronic structure as that of a high-quality bulk single crystal Fe_1.14Te. Our results suggest that MBE with Te-limited growth may provide an opportunity to synthesize FeTe films with smaller amounts of excess Fe as to come closer to a possible superconducting phase.