Iron-based superconductors

The recent discovery of the Fe-based superconductors provided a new material base for studying the mechanism of high temperature superconductivity. Some analogies with the family of high-Tc cuprate superconductors are noticeable like the occurrence of superconductivity (SC) in the proximity of an anti-ferromagnetic phase and doping as a tool to induce SC. The semi-metallic nature of the pnictides contrasts with the insulating ground state in the cuprate parent compounds. The two most commonly investigated families are those of Fe-pnictides: “1111” family RFeAsO (R=Nd,Sm,Pr,La) and “122” family AFe2As2 (A=Ca,Sr,Ba,Eu). We study the pressure dependence of the resistivity and thermoelectric power of them.

Typical flux-grown single crystals of BaFe2As2. The scale is in millimeters (Courtesy of Dave Mandrus).

Thermoelectric power of BaFe2As2 under pressure. The arrow indicates the direction of the increasing pressure.

More precisely, we have performed an extensive study of the pressure dependence of the compounds  Ba(Fe1-xCox)As2, Cs0.8(FeSe0.98)2,Ba0.68K0.32Fe2As2 and Fe1+yTe1-xSex in single crystalline form. 

References:

[1] S. Arsenijević, R. Gaál, A. S. Sefat, M. A. McGuire, B. C. Sales, D. Mandrus, and L. Forró, Phys. Rev. B 84, 075148 (2011).