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Register a new userSuperconductivity at 25K under hydrostatic pressure for FeTe0.5Se0.5 superconductor
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We report the impact of hydrostatic pressure on the superconductivity and normal state resistivity of FeTe0.5Se0.5 superconductor. At the ambient pressure the FeTe0.5Se0.5 compound shows the superconducting transition temperature Tconset at above 13K and TcR=0 at 11.5K. We measure pressure dependent resistivity from 250K to 5K, which shows that the normal state resistivity increases initially for the applied pressures of up to 0.55GPa and then the same is decreased monotonically with increasing pressure of up to 1.97GPa. On the other hand the superconducting transition temperatures (Tconset and TcR=0) increase monotonically with increasing pressure. Namely the Tconset increases from 13K to 25K and TcR=0 from 11.5K to 20K for the pressures range of 0-1.97GPa. Our results suggest that superconductivity in this class of Fe-based compounds is very sensitive to pressure as the estimated pressure coefficient dTc(onset)/dP is 5.8K/GPa. It may be suggested that FeTe0.5Se0.5 superconductor is a strong electron correlated system. The enhancement of Tc with applying pressure is mainly attributed to an increase of charge carriers at Fermi surface.
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We report the effect of hydrostatic pressure (0-1.97GPa) on the superconductivity of BiS2 based CeO0.5F0.5BiS2 compound. The CeO0.5F0.5BiS2 superconductor was synthesized by the solid state reaction route and the compound is crystallized in tetragonal P4/nmm space group. The studied compound shows superconductivity with transition temperature of 2.5K (Tconset) at ambient pressure, which has been enhanced to 8 K at applied pressure of 1.97 GPa. The observed normal resistivity exhibited semiconducting behavior. The data of normal state resistivity R(T) has been fitted by activation type equation and it is found that the energy gap is significantly reduced with pressure. Resistivity measurements under magnetic field for the highest applied pressure of 1.97GPa (Tconset = 8K) exhibits the upper critical field of above 5Tesla. The observation of fourfold increase in Tc accompanied with improved normal state conduction under hydrostatic pressure on CeO0.5F0.5BiS2 superconductor calls for the attention of solid state physics community.
We have investigated the pressure effect on the newly discovered samarium doped La1-xSmxO0.5F0.5BiS2 superconductors. More than threefold increase in Tc (10.3 K) is observed with external pressure (at ~1.74 GPa at a rate of 4.08 K/GPa)) for x = 0.2 composition. There is a concomitant large improvement in the quality of the superconducting transition. Beyond this pressure Tc decreases monotonously at the rate of -2.09 K/GPa. In the x = 0.8 sample, we do not observe any enhancement in Tc with application of pressure (up to 1.76 GPa). The semiconducting behavior observed in the normal state resistivity of both of the samples is significantly subdued with the application of pressure which, if interpreted invoking thermal activation process, implies that the activation energy gap of the carriers is significantly reduced with pressure. We believe these observations should generate further interest in the La1-xSmxO0.5F0.5BiS2 superconductors.
We investigate the hydrostatic pressure dependence of interfacial superconductivity occurring at the atomically sharp interface between two non-superconducting materials: the topological insulator (TI) Bi2Te3 and the parent compound Fe1+yTe of the chalcogenide iron based superconductors. Under pressure, a significant increase in the superconducting transition temperature Tc is observed. We trace the pressure dependence of a superconducting twin gap structure by Andreev reflection point contact spectroscopy (PCARS), which shows that a large superconducting gap associated with the interfacial superconductivity increases along with Tc. A second smaller gap, which is attributed to proximity-induced superconductivity in the TI layer, increases first, but then reaches a maximum and appears to be gradually suppressed at higher pressure. We interpret our data in the context of a pressure-induced doping effect of the interface, in which charge is transferred from the TI layer to the interface and the interfacial superconductivity is enhanced. This demonstrates the important role of the TI in the interfacial superconductivity mechanism.
In this communication, we report the temperature dependence (3 to 300K) of the electrical resistivity of BiS2 based layered PrO0.5F0.5BiS2 superconductor at ambient and hydrostatic pressure of up to 3GPa. It is observed that Tc increases with pressure at the rate of dTc/dP=0.45/GPa for PrO0.5F0.5BiS2 compound. It is envisaged that one may increase the Superconducting transition temperature (Tc) of recently discovered PrO0.5F0.5BiS2 superconductor by applying hydrostatic external or internal chemical pressure via suitable on site substitutions.
We report the appearance of superconductivity under hydrostatic pressure (0.35 to 2.5GPa) in Sr0.5RE0.5FBiS2 with RE = Ce, Nd, Pr and Sm. The studied compounds, synthesized by solid state reaction route, are crystallized in tetragonal P4/nmm space group. At ambient pressure though the RE = Ce exhibit the onset of superconductivity below 2.5K, the Nd, Pr and Sm samples are not superconducting down to 2K. With application of hydrostatic pressure (up to 2.5GPa), superconducting transition temperature is increased to around 10K for all the studied samples. The magneto-transport measurements are carried out on all the samples with maximum Tc i.e., at under 2.5GPa pressure and their upper critical fields are determined. The new superconducting compounds appear to be quite robust against magnetic field but within Pauli paramagnetic limit. The new superconducting compounds with various RE (Ce, Nd, Pr and Sm) belonging to Sr0.5La0.5FBiS2 family are successfully synthesized for the first time and superconductivity is induced in them under hydrostatic pressure.
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