B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine
Institute of Experimental Mineralogy RAS, Chernogolovka 142432, Russia
M.V. Lomonosov Moscow State University, Moscow 119991, Russia
M.V. Lomonosov Moscow State University, Moscow 119991, Russia Ural Federal University, Mira st. 19, Ekaterinburg 620002, Russia pos Анотація:
Received December 16, 2014
The influence of uniform pressures P up to 5 kbar on the superconducting transition temperature Tc was studied for the FeSe1–xTex (x = 0, 0.85, 0.88, and 0.90) system. For the first time, we observed a change in sign of the pressure effect on Tc when going from FeSe to tellurium rich alloys. This has allowed to specify the pressure derivative dTc/dP for the system as a function of composition. The observed dependence was compared with results of the ab initio calculations of electronic structure and magnetism of FeSe, FeTe and FeSe0.5Te0.5, and also with our recent experimental data on pressure effects on magnetic susceptibilities of FeSe and FeTe compounds in the normal state. This comparison demonstrates a competing interplay between superconductivity and magnetism in tellurium rich FeSe1–xTex compounds.
PACS: 74.62.–c Transition temperature variations, phase diagrams; PACS: 74.62.Fj Effects of pressure; PACS: 74.70.Xa Pnictides and chalcogenides; PACS: 75.10.Lp Band and itinerant models.
Key words: iron superconductors, FeSe1–xTex, electronic structure, magnetic susceptibility, pressure effects.