Pressure-induced enhancement of superconductivity and suppression of semiconducting behavior inLnO0.5F

Abstract

Electrical resistivity measurements as a function of temperature between 1 K and 300 K were performed at various pressures up to 3 GPa on the superconducting layered compounds LnO0.5F0.5BiS2 (Ln = La, Ce). At atmospheric pressure, LaO0.5F0.5BiS2 and CeO0.5F0.5BiS2 have superconducting critical temperatures, Tc, of 3.3 K and 2.3 K, respectively. For both compounds, the superconducting critical temperature Tc initially increases, reaches a maximum value of 10.1 K for LaO0.5F0.5BiS2 and 6.7 K for CeO0.5F0.5BiS2, and then gradually decreases with increasing pressure. Both samples also exhibit transient behavior in the region between the lower Tc phase near atmospheric pressure and the higher Tc phase. This region is characterized by a broadening of the superconducting transition, in which Tc and the transition width ∆Tc are reversible with increasing and decreasing pressure. There is also an appreciable pressure-induced and hysteretic suppression of semiconducting behavior up to the pressure at which the maximum value of Tc is found. At pressures above the value at which the maximum in Tc occurs, there is a gradual decrease of Tc and further suppression of the semiconducting behavior with pressure, both of which are reversible.

Significant enhancement of superconductivity under Hydrostatic pressure in CeO0.5F0.5BiS2 superconductor

“…An increase in T c from 2.2K at ambient pressure to above 6K was observed at 1.64GPa, which remains nearly unaltered for studied higher pressures of up to 2.47GPa [14]. In the present report, the compound CeO 0.5 F 0.5 BiS 2 has been subjected to pressure dependent electrical resistivity in the temperature range 300 K down to 2K at several applied pressures of 0 to 1.97GPa to reproduce and test the earlier reported interesting result [14,15]. Our results are though qualitatively similar to that as reported earlier [14,15], yet quantitatively different.…”

“…Worth mentioning is the fact that impact of hydrostatic pressure on superconductivity of CeO 0.5 F 0.5 BiS 2 has already been reported very recently [14,15]. An increase in T c from 2.2K at ambient pressure to above 6K was observed at 1.64GPa, which remains nearly unaltered for studied higher pressures of up to 2.47GPa [14].…”

“…Both the experimental and theoretical studies of BiS 2 based superconductors have progressed well but the studies related to impact of external high pressure on the superconducting properties of this compound are limited to select groups only [14][15][16]. The application of external pressure may effectively change the superconducting properties such as transition temperature T c of these BiS 2 compounds.…”

Synthesis and Properties of SmO0.5F0.5BiS2 and Enhancement in Tc in La1–ySmyO0.5F0.5BiS2

“…9 Superconductivity in LnO 1-x F x BiS 2 with Ln = Ce, Pr, Nd and Yb also followed soon. [10][11][12][13][14][15][16] T c is enhanced by chemical pressure [18][19][20] or external applied pressure [22][23][24][25][26][27] as observed for LnOFeAs 28 for example in LnO 1-x F x BiS 2 , a slight enhancement in T c has been reported by substituting Se at the S sites or by inter-mixing rare earth ions. [18][19][20][21] Hole doping via alkali earthmetal-substitution at Ln-site did not yield superconductivity.…”

Observation of Supermodulation in LaO0.5F0.5BiSe2 by Scanning Tunneling Microscopy and Spectroscopy

“…These materials have been intensively investigated because their layered structure, which is composed of superconducting layers and blocking layers, is similar to those of cuprates and iron-based superconductors. Although, the superconducting transition temperature (T c ) of these BiS 2 -based materials is 3-5 K, T c strongly depends on external pressure or high-pressure annealing [2,[28][29][30][31][32][33]. For instance, LaO 1-x F x BiS 2 showing T c of around 3 K shows superconductivity at around 10 K when an external pressure is applied.…”