Seminarium w Instytucie Niskich Temperatur i Badań Strukturalnych PAN
bud. II, sala 6
Enhancement of Superconductivity in FeSe layered materials
Yoshihiko Takano
MANA, National Institute for Materials Science, Tsukuba, Japan and University of Tsukuba, Japan
Layer structured iron chalcogenide, FeSe, has the simplest crystal structures among iron-based superconductors. It is thought that the iron chalcogenide is suitable material to elucidate the mechanism of Fe-based superconductivity. Superconducting transition temperature is around 10 K at ambient pressure. However it was reported that the Tc increased up to 37 K under high pressure [1-3]. Very recently, we have observed Tc(onset) around 44K in single crystalline FeSe under relatively uniaxial pressure using new DAC with metallic diamond electrode, which indicate the potential for higher-Tc in FeSe superconductor.
The Tc~44K is also observed in K intercalated FeSe. Single crystal samples of KFe2Se2 were prepared by a “one-step method” [4] with/without quenching. The samples quenched at 500-700 °C showed a sharp superconducting transition around 33K, and its shielding volume fraction was almost 100 %. On the other hand, the slow-cooled sample showed broad superconducting transitions with relatively low shielding volume fractions. However we found that Tc onset was elevated up to 44K in resistivity measurement [5]. Using high-temperature X-ray analysis and SEM measurement, we have successfully distinguished the origin of Tc~44K in FeSe layered system.
References:
[1] Y. Mizuguchi et al., Appl. Phys. Lett. 93, 152505 (2008).
[2] S. Margadonna et al., Phys. Rev. B 80, 064506 (2009).
[3] S. Masaki et al., J. Phys. Soc. Jpn. 78, 063704 (2009).
[4] T. Ozaki et al., Euro. Phys. Lett., 98, 27002 (2012).
[5] M. Tanaka et al., J. Phys. Soc. Jpn. 85, pp. 044710(2016).
Seminarium Oddziału Badań Magnetyków i Oddziału Niskich Temperatur i Nadprzewodnictwa
