Magnetism in Fe-based superconductors

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Journal of Physics: Condensed Matter

DOI:https://doi.org/10.1088/0953-8984/22/20/203203· OSTI ID:983143

Lumsden, Mark D ^[1]; Christianson, Andrew D ^[1]

---

1. ORNL

In this review, we present a summary of experimental studies of magnetism in Fe-based superconductors. The doping dependent phase diagram shows strong similarities to the generic phase diagram of the cuprates. Parent compounds exhibit magnetic order together with a structural phase transition both of which are progressively suppressed with doping allowing superconductivity to emerge. The stripe-like spin arrangement of Fe moments in the magnetically ordered state shows the identical in-plane structure for the RFeAsO (R=rare earth) and AFe2As2 (A=Sr, Ca, Ba, Eu and K) parent compounds, notably different than the spin configuration of the cuprates. Interestingly, Fe1+yTe orders with a different spin order despite very similar Fermi surface topology. Studies of the spin dynamics in the parent compounds shows that the interactions are best characterized as anisotropic three-dimensional (3D) interactions. Despite the room temperature tetragonal structure, analysis of the low temperature spin waves under the assumption of a Heisenberg Hamiltonian indicates strong in-plane anisotropy with a significant next-near neighbor interaction. In the superconducting state, a resonance, localized in both wavevector and energy is observed in the spin excitation spectrum as in the cuprates. This resonance is observed at a wavevector compatible with a Fermi surface nesting instability independent of the magnetic ordering of the relevant parent compound. The resonance energy (Er) scales with superconducting transition temperature (TC) as Er 4.9 kBTC consistent with the canonical value of 5 kBTC observed in the cuprates. Moreover, the relationship between the resonance energy and the superconducting gap, , is similar to that observed in many unconventional superconductors (Er/2 0.64).

• Research Organization: Oak Ridge National Laboratory (ORNL); High Flux Isotope Reactor; Spallation Neutron Source
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 983143
• Journal Information: Journal of Physics: Condensed Matter, Journal Name: Journal of Physics: Condensed Matter Journal Issue: 20 Vol. 22; ISSN 0953-8984; ISSN 1361-648X
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANISOTROPY
CONFIGURATION
CUPRATES
EXCITATION
FERMI LEVEL
HAMILTONIANS
INSTABILITY
MAGNETISM
MESONS
PHASE DIAGRAMS
RESONANCE
SPIN
SPIN WAVES
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TOPOLOGY
TRANSITION TEMPERATURE