Spintronic devices, devices that rely upon the spin of the conduction electron to control device properties, are of increasing scientific and commercial interest. These devices commonly are heterostructures with ferromagnetic metals used as spin injectors. The performance of these heterostructured devices can be optimized by using a 100% spin-polarized ferromagnet. Recent band-structure calculations predict that the Heusler alloy ${\mathrm{Co}}_2\mathrm{MnSi}$ should be a 100% spin-polarized ferromagnet. However, band-structure calculations further suggest that chemical disorder in the ${\mathrm{Co}}_2\mathrm{MnSi}$ lattice should lower the degree of spin polarization. In this work, we present neutron diffraction and extended x-ray-absorption fine-structure measurements (EXAFS) on bulk ${\mathrm{Co}}_2\mathrm{MnSi},$ which reveal extensive chemical disordering even in pure-phase samples and discuss the limitations of EXAFS in measuring this sort of disorder.

• Received 14 June 2001

DOI:https://doi.org/10.1103/PhysRevB.65.184431