Magnetic properties of novel FeSe(Te) superconductors

• DOI: 10.1016/j.jmmm.2012.02.065
• Publication Date: 2012-02-25T11:04:18Z
• Authors: G.E. Grechnev; A.S. Panfilov; A.V. Fedorchenko; V.A. Desnenko; S.L. Gnatchenko; V. Tsurkan; J. Deisenhofer; A. Loidl; D.A. Chareev; O.S. Volkova; A.N. Vasiliev
• Keywords: ddc:530; 0103 physical sciences; Iron-based superconductor; FeSe; FeTe; electronic structure; magnetization; Pressure effect; 01 natural sciences; 7. Clean energy

Abstract Magnetization studies were carried out for the novel FeSe 1− x Te x superconductors ( 0 ≤ x ≤ 1 ) to investigate a behavior of the intrinsic magnetic susceptibility χ in the normal state. The magnetic susceptibility was found to increase gradually with Te content. The temperature dependencies of the magnetic susceptibility χ and its anisotropy Δ χ = χ ∥ − χ ⊥ were measured for FeSe in the temperature range 4.2–300 K, and a growth of susceptibility with temperature was revealed. For FeTe a substantial increase of χ under pressure was found. Ab initio calculations of the band structure and magnetic susceptibility have shown, that FeSe 1− x Te x systems are close to magnetic instability with dominating enhanced spin paramagnetism. The calculated paramagnetic susceptibility exhibits a strong dependence on the unit cell volume V and especially the height of chalcogen species from the Fe plane. With appropriate values of these parameters the calculations have reproduced the experimental data on χ ( T ) and χ ( P ) for FeSe and FeTe, respectively.