High Pressure Effects on Fe-based Chalcogenide Superconductors Revisited

MARICEL RODRIGUEZ, CARLOS ACHA Y GRISELDA POLLA

Buenos Aires

Congreso; 27 Congreso Internacional de Bajas Temperaturas (LT27); 2014

We have measured the pressure sensitivity of thesuperconducting critical temperature (Tc) of FeSe0.5Te0.5 single crystals forpressures up to 20 GPa. We observed that at first, Tc increases with increasingpressure (P), reaching a maximum value at P $sim$ 5 GPa and decreasing for afurther increase of pressure, similarly to previously published results [1-2]. Surprisingly,for P > 11 GPa a second parabolic dependence is observed indicating there-emergence o the superconducting state. By considering our results and thosereported for other Fe-based superconductors (pnictides and chalcogenides),  we propose a phenomenological model thatdescribes the pressure dependence of Tc of these materials, based on the evolutionof structural parameters [anion height, regularity of the Fe(Se,Te) tetrahedra]with pressure. More importantly, our experimental results providethe opportunity to observe the evolution of the superconducting state in tworegions with a different sensitivity to structural distortions. This particularaspect should be taken into account for a model of high critical temperaturesuperconductivity on Fe-based superconductors.