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Spin densities in hexaborides and magnetic superconductorsJ A Duffy
Department of Physics, University of Warwick, Coventry, CV4 7AL (j.a.duffy@warwick.ac.uk)
Magnetic Compton scattering is a technique whereby the spin-dependent electron momentum density in ferromagnets can be probed. The spin-polarised Compton profile is a 1-dimensional integral of the momentum space spin density. The total spin moment can be directly obtained via the integrated scattering cross section, whilst the lineshape is determined by the nature of the electronic orbitals or bands on which the magnetism resides. Spin-polarised Compton scattering is closely related to the magnetic form factor measurements performed using neutron and x-ray diffraction methods. The method is particularly useful for studying both itinerant moment systems, and materials where there is a combination of localised and itinerant moments. The hexaborides exhibit a wide range of electronic properties. Data will be presented for the heavy Fermion system CeB6 and the controversial ferromagnet Ca1-XLaXB6. Our studies of magnetic superconductors include ZrZn2, in the normal state, to study the 4d moment, and for comparison with electronic structure calculations. We have also studied ErNi2B2C, where the measurements show clear evidence for the existence of a weak ferromagnetic state below 2.3K, within the superconducting state. Finally, present developments of the method, including use of higher magnetic fields, and high pressures, will be discussed.
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