CHARGE-DENSITY WAVES AND STRAIN WAVES IN THIN EPITAXIAL CR(001) FILMSON NB

We have investigated the magnetic structure of thin epitaxial (001)-or iented Cr films grown on a Nb buffer layer on sapphire. By means of x- ray diffraction measurements the charge density waves (CDW) and strain waves (SW) in Cr films with thicknesses between 500 and 3000 Angstrom have been studied. The results show that there exists an orientationa l pinning effect at both the Cr surface and the interface between Cr a nd the Nb buffer layer which causes an enlargement of the CDW-SW perio d, and a single a domain mode having a q vector pointing perpendicular to the surface. This pinning behavior relaxes with increasing film th ickness.