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Static and dynamic magnetism in underdoped superconductor BaFe1.92Co0.08As2
A D Christianson1, M D Lumsden, S E Nagler
1Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Physical Review Letters
|October 2, 2009
Summary
Neutron scattering reveals that in BaFe1.92Co0.08As2, magnetic order competes with superconductivity. Cooling below the critical temperature (TC) causes a spin resonance, indicating a spectral weight shift.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Superconductivity
Background:
- Iron-based superconductors exhibit complex magnetic and electronic properties.
- Understanding the interplay between static magnetic order and superconductivity is crucial for novel material design.
Purpose of the Study:
- To investigate the spin dynamics and magnetic order in BaFe1.92Co0.08As2 using neutron scattering.
- To elucidate the relationship between magnetic Bragg peak intensity, spin excitations, and superconductivity.
Main Methods:
- Neutron scattering measurements on single crystals of BaFe1.92Co0.08As2.
- Analysis of magnetic Bragg peak intensity and spin excitation energies as a function of temperature.
Main Results:
- A 6% reduction in magnetic Bragg peak intensity upon cooling below the critical temperature (TC).
- Observation of an 8 meV spin gap with anisotropic three-dimensional interactions.
- Appearance of a spin resonance at approximately 4.5(0.5) meV below TC.
- No further gapping of spin excitations observed down to 2 meV.
Conclusions:
- The findings suggest a redistribution of spectral weight from static magnetic order to a spin resonance.
- This spectral weight shift demonstrates a direct competition between static magnetic order and superconductivity in BaFe1.92Co0.08As2.
- The observed spin resonance is consistent with phenomena in other iron-based superconductors.
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