HIGH PRESSURE EFFECTS ON FE-BASED CHALCOGENIDE SUPERCONDUCTORS REVISITED

MARICEL GABRIELA RODRÍGUEZ; GRISELDA POLLA; C. ACHA

Buenos Aires

Conferencia; XXVII International Conference on low temperature physics (LT27); 2014

Departamento de Física - FCEyN - UBA e IFIBA-CONICET

We have measured the pressure sensitivity of the superconducting critical temperature (Tc) of FeSe0.5Te0.5 single crystals for pressures up to 20 GPa. We observed that at first, Tc increases with increasing pressure (P), reaching a maximum value at P $sim$ 5 GPa and decreasing for a further increase of pressure, similarly to previously published results [1-2]. Surprisingly, for P > 11 GPa a second parabolic dependence is observed indicating the re-emergence of the superconducting state. By considering our results and those reported for other Fe-based superconductors (pnictides and chalcogenides), we propose a phenomenological model that describes the pressure dependence of Tc of these materials, based on the evolution of structural parameters [anion height, regularity of the Fe(Se,Te) tetrahedra] with pressure. More importantly, our experimental results provide the opportunity to observe the evolution of the superconducting state in two regions with a different sensitivity to structural distortions. This particular aspect should be taken into account for a model of high critical temperature superconductivity on Fe-based superconductors.