Effect of Sb and Si doping on the superconducting properties of FeSe0.9

Abstract

a b s t r a c tIn the present work, we have studied the effect of doping Sb and Si at the Se-site of FeSe 0.9 on the superconducting properties, such as transition temperature (T c ), upper critical field (H c2 ) and irreversibility field (H irr ). The polycrystalline samples have been synthesized via two step solid state reaction route with nominal compositions Fe[Se 1Àx (Sb/Si) x ] 0.9 (x = 0.0, 0.05, 0.10, 0.15 and 0.20). The X-ray diffraction resultsshow the presence of tetragonal a-FeSe phase with the P4/nmm space group symmetry in all the samples.The highest superconducting onset temperatures, T onset c $ 9:42 K and 9:20 K, respectively, for Si and Sb doped samples have been found for x = 0.05. The temperature dependence of H c2 (T) and H irr (T) have been calculated from the magnetoresistance data using the criteria of 90% and 10% of normal state resistivity (q n ) values, respectively. The values of H c2 (0) estimated from Werthamer-Helfand-Hohenberg (WHH) and Ginzburg-Landau (GL) theories are found to follow the same trends and maximum H c2 (0) is found for the composition x = 0.10 for both the Si and Sb doped samples. The irreversibility field, H irr and activation energy, U 0 have also been calculated to study the vortex motion behavior of the samples. A clear cut correlation between H irr and U 0 has been found.

High field superconducting properties of Ba(Fe1−xCox)2As2 thin films

“…3 because of the crossover to the regime of single vortex pinning where is constant. Similar dependencies have recently been found for polycrystalline MgB 2 , NbSe 2 36, and FeSe3738, as well as LiFeAs single crystals39.…”

Improvement of the superconducting properties of polycrystalline FeSe by silver addition

“…When comparing the 00l peaks of tetragonal phase for FeSeAg0 and FeSeAg10 (or FeSeAg6) samples a noticeable systematic shift of all peaks is observed (shown in Table 1). An XRD peaks displacement smaller by one order of magnitude is reported by Sudesh et all [10] and Pandya et all [11] in FeSe 1-x Sb x . This is reasonable because the atomic radius of Ag is larger than that of Sb (160 and 145 pm respectively).…”

A simple method for preparing superconducting FeSe pellets without sealing in evacuated silica tubes

“…So far, most reported preparation conditions involve sealing in evacuated quartz ampoules, heating most often well above the temperature, below which tetragonal FeSe is stable, followed or not by annealing at 300 °C ≤ T ≤ 460 °C [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In some cases, several heat treatments are performed, requiring re-sealing in new evacuated ampoules [14][15][16][17][18][19][20][21][22]. Although this processing route usually results in good samples, it is time and resources consuming, because the silica tubes are generally broken and disposed of at the end of each heat treatment, and thus not optimized for potential large-scale production.…”