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Anisotropic three-dimensional magnetism in CaFe2As2.
R J McQueeney1, S O Diallo, V P Antropov
1Department of Physics & Astronomy, Iowa State University, Ames, Iowa 50011, USA.
Physical Review Letters
|December 31, 2008
Summary
Magnetic excitations in CaFe2As2 reveal exceptionally large spin wave velocities in Fe layers, comparable to cuprates. This anisotropic three-dimensional magnetism contrasts with two-dimensional cuprates and is supported by theoretical calculations.
Area of Science:
- Condensed matter physics
- Materials science
- Magnetism
Background:
- CaFe2As2 is an iron-based superconductor.
- Understanding magnetic excitations is crucial for elucidating superconductivity mechanisms.
Purpose of the Study:
- To investigate the magnetic excitations in CaFe2As2 using inelastic neutron scattering.
- To characterize the spin wave velocity and dimensionality of magnetism in CaFe2As2.
Main Methods:
- Inelastic neutron scattering (INS) measurements were performed on CaFe2As2.
- Analysis of magnetic excitation spectra to determine spin wave velocities.
- Comparison with theoretical predictions from band structure calculations.
Main Results:
- Observed exceptionally large spin wave velocity in the Fe layers, comparable to cuprates.
- Determined spin wave velocity perpendicular to the layers is significant, indicating anisotropic three-dimensional magnetism.
- Experimental findings are consistent with exchange constants derived from band structure calculations.
Conclusions:
- The magnetism in CaFe2As2 is anisotropic three-dimensional, not two-dimensional like cuprates.
- The large spin wave velocity contributes to the understanding of magnetic properties in iron-based superconductors.
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