First Investigation of Pressure Effects on Transition from Superconductive to Metallic Phase in FeSe_0.5Te_0.5

Abstract

High-pressure resistivity experiments were performed on FeSe 0:5 Te 0:5 . The onset temperature of T c (T onset c ) increases rapidly from 13.5 to 26.2 K upon applying pressure up to 2 GPa. Above 2 GPa, T c decreases linearly and the metallic phase was observed at P ¼ 14 GPa. The same relationship between normalized T c and pressure in both FeSe 0:5 Te 0:5 and FeSe suggests a universal pressure dependence in this system. This report presents the first observation of a phase transition from the superconducting to the metallic phase on the P-T c phase diagram.

Interrelation of superconductivity and magnetism in FeSe1−xTex compounds. Pressure effects

“…Also, in FeSe compound the extremely large rise of T c up to 35 ÷ 37 K takes place with pressure P ∼70-80 kbar [10,11]. The similar behavior of T c under pressure was also observed in FeSe 0.5 Te 0.5 compound [12,13]. With further increase of x in FeSe 1−x Te x a tendency to reduction of the positive pressure effect is expected with even probable change of its sign, as it was observed in the related tellurium rich FeS 0.2 Te 0.8 alloy [9].…”

“…For the region of small pressures (0÷10 kbar) we established the growth of N (E F ) with the rate of dln N (E F )/dP ≃ 1 Mbar −1 . We should note that such behavior of N (E F ) correlates with increase of the superconducting transition temperature in FeSe 0.5 Te 0.5 under pressure [12,13].…”

Review of Fe Chalcogenides as the Simplest Fe-Based Superconductor

“…As observed in FeSe, positive pressure effect was observed for FeTe 1Àx Se x . 25,41,42) Figure 36(a) shows the temperature dependence of resistivity for Fe 1:03 Te 0:43 Se 0:57 under high pressure up to 11.9 GPa. The crystal structural analysis under high pressure was also performed using synchrotron x-ray diffraction.…”

The Pressure Effects on Electronic Structure of Iron Chalcogenide Superconductors FeSe1-xTex

“…Tellurium substitution into selenium sites raises the critical temperature T C in FeSe 1−x Te x up to 15 K for x = 0.5 [35]. Additionally, T C increases to 37 K for FeSe [610] and to 26 K for FeSe 0.5 Te 0.5 [11,12] under external pressure. On the other hand, the end member FeTe (x = 1) is no longer superconducting, but shows antiferromagnetic phase at low temperatures.…”