Pressure cycle of superconducting Cs0.8Fe2Se2 : A transport study

Superconductivity and magnetism in Rb0.8Fe1.6Se2under pressure

“…These results are in excellent agreement with recent pressure-dependent electrical resistivity studies of Rb 0.8 Fe 2 Se 2 , especially with the steep decrease of T c from 15.5 K at 5 GPa to zero at 5.6 GPa [15]. It resembles also the pressure behavior of T c in the related Cs 0.8 Fe 2 Se 2 compound [16]. In K 0.8 Fe 1.7 Se 2 and K 0.8 Fe 1.78 Se 2 , however, a more continuous decrease of T c up to critical pressures around 9 GPa is reported [12].…”

“…T c was determined from the intersection of two extrapolated straight lines drawn through the data points in the normal state and the steepest part in the superconducting state. Similarly to observations in the K-and Cs-intercalated superconductors [12][13][14]16], T c of Rb 0.8 Fe 1.6 Se 2 shows a moderate decrease with a rate of -2.1 K/GPa up to 5 GPa. Then, a sudden suppression of the diamagnetic ZFC signal occurs at pressures close to 6 GPa and T c drops to zero.…”

“…The iron-based superconductors exhibit a pronounced dependence of the superconducting transition temperature on pressure: T c of the simplest Fe-based superconductor, FeSe, amounts to 8 K at ambient pressure and reaches 37 K around 8 GPa [10,11]. However, recent studies of K 0.8 Fe 1.7 Se 2 [12][13][14], Rb 0.8 Fe 2 Se 2 [15] and Cs 0.8 Fe 2 Se 2 [13,16] have shown that T c is only slightly increased by pressure to a maximum value of 33 K and superconductivity is completely suppressed by further increasing pressures up to 9 GPa. The origin of the suppression of superconductivity in A x Fe 2−y Se 2 systems with pressure is still an open question.…”

High-Pressure Single-Crystal Neutron Scattering Study of Magnetic and Fe Vacancy Orders in (Tl,Rb) 2 Fe 4 Se 5 Superconductor

“…The T c has been suppressed to zero at critical pressure P c ≈ 6 GPa for A= Rb [19,20], 8 GPa for A= Cs [21], and 9 GPa for A= K and Tl-Rb superconductors [22]. In the latter study, superconductivity of a higher T c = 48 K is reported to re-emerge between 11 and 13 GPa [22].…”

“…Detected in the 245 superconductors is the alkaline metal deficient A x Fe 2 Se 2 (x ∼ 0.3-0.6) phase embedded in √ 5 × √ 5 iron vacancy ordered superstructure [12][13][14], forming various microstructure patterns in plane [15,16] High pressure adds an additional dimension to the complex composition phase-diagram of 245 superconductors [8], offering a "clean" way to investigate the relation among various phases [18,19]. The T c has been suppressed to zero at critical pressure P c ≈ 6 GPa for A= Rb [19,20], 8 GPa for A= Cs [21], and 9 GPa for A= K and Tl-Rb superconductors [22]. In the latter study, superconductivity of a higher T c = 48 K is reported to re-emerge between 11 and 13 GPa [22].…”