An overview on iron based superconductors

Abstract

The discovery of superconductivity at relatively higher temperatures in a non-cuprate system, LnFeAsO 1−x F x (Ln = lanthanides) has created tremendous activity among the reseachers in this field. This review is an overview on the present status and the future scope for iron pnictides. The various structural categories of iron based superconductors, the structural aspects, different preparation techniques of the material and the necessity for its optimization are discussed. The highlighting features of iron pnictide, i.e. the very high upper critical field, moderate magneto-transport and thermal properties, are also included. The article gives a summary of the prevailing arguments of researchers to relate the material to cuprates and also the comparative features of classical and MgB 2 superconductors. The existing challenges, such as optimizing synthesis methods for technological applications and clarifying the ambiguity in the superconducting mechanism and the flexibility of the material for any site substitution, will keep iron based superconductors on the frontiers of research for a long time, in parallel to HTS.

Electrical resistivity of single crystals of LaFeAsO under applied pressure

“…The behavior of materials within this genus of the iron-pnictide family has, in some cases, been shown to be very sensitive to doping, impurities, and oxygen vacancies. 5,13,21,22 In our earlier study 4,6 on these samples, we measured lower transition temperatures, T SDW and T ST , relative to results from measurements of polycrystals and other single crystals at ambient pressure. 9,23 We compare the results of ambient pressure measurements on our single crystals of LaFeAsO to similar measurements discussed by Yan et al in the Results and Discussion section of this paper.…”

“…[3][4][5][6] As a function of chemical substitution or applied pressure, the phase diagrams of these materials exhibit a rich interplay of different phenomena, including structural transitions, commensurate and incommensurate spin-density wave (SDW) ordering, and high temperature superconductivity. [5][6][7][8][9][10][11][12][13] In several iron-based materials, the appearance of superconductivity occurs following a smooth suppression of SDW order. Among the materials in which such a continuous suppression is observed are, e.g., BaFe 2 As 2 (under both chemical substitution and applied pressure) 14 and fluorine-substituted CeFeAsO 1−x F x .…”

dc Josephson Current Between an Isotropic and a d-Wave or Extended s-Wave Partially Gapped Charge Density Wave Superconductor

“…Similar studies of iron-based superconductors with doping-dependent spin density waves (SDWs) would also be of benefit (see, e.g., recent Reviews [78,[269][270][271][272][273][274][275]), since CDW and SDW superconductors have similar, although not identical, properties [123][124][125].…”

Solid state synthesis and characterization of bulk FeTe0.5Se0.5superconductors

“…Fe-As layers, which are negatively charged, and Ln-O layers (Ln: lanthanides), positively charged, are simply arranged along the c-axis. The Ln-O layers are insulating nature and the Fe-As layers are responsible from the conducting mechanism [14,15]. The FeSe phase, called as "11-phase" with T c =8 K, which is a derivative of FeAs family, is composed of tetrahedral stacks of Fe 2 Se 2 layers which have edge sharing peculiarity and behave as conducting layers similar to B 2 layers in MgB 2 metallic superconducting alloys [7,16].…”