EFFORTS TO PREPARE NEW IRON-BASED SUPERCONDUCTORS

 

Efrain E. Rodriguez,1 Pawel Zajdel,2 Kevin Kirshenbaum,3 Johnpierre Paglione,3 Mark A. Green1

 

  1. NIST Center for Neutron Research, NIST, Gaithersburg, MD 20899
  2. Division of Physics of Crystals, University of Silesia, 40-007 Katowice, Poland
  3. Center for Nanophysics and Advanced Materials, University of Maryland, College Park, MD 20742

 

 

 

Studies of superconductivity in iron-based pnictides, oxypnictides, and chalcogenides have demonstrated how these materials can exhibit strikingly similar transport behavior despite having diverse crystal structures and chemical stoichiometries.  Similarities among some of the disparate systems include metallic conductivity and antiferromagnetic ordering of the Fe magnetic moments in the undoped parent phases, e.g. LaOFeAs[1] and BaFe2As2.[2]  However, the relationship between the antiferromagnetic ordering and superconductivity remains an open question, especially since magnetic ordering remains absent in FeSe.[3]   One  feature common to all, however, is the topology of the Fe cation lattice.  Arranged in a square planar lattice, the Fe cations are tetrahedrally coordinated to four anions, whether they be P, As, Se, or Te. This two-dimensional arrangement is known as the anti-PbO-type structure, and our efforts are in recreating this topology in new oxypnicitdes and chalcogenides of iron in order to search for evidence of superconductivity.  Either way, we aim to study the nature of the itinerant magnetism (or lack thereof) in these new Fe-based materials with neutron scattering and transport measurements, our focus being on non-arsenic containing compounds.  In addition, we present the magnetic structure and properties of the simple binary phosphide and arsenide of iron in order to better understand the magnetism, bonding, and properties of iron pnictides.

 

1. C. de la Cruz et al., Nature, 63 (2007) 899.

2. M. Rotter et al., Phys. Rev. Lett., 101 (2008) 107006.

3. H. Kotegawa et al., J. Phys. Soc. Japan, 77 (2008) 113703.