The magnetoelastic coupling constant B2 of epitaxial Fe(001) films

Magnetoelastic (ME) coupling, a property of major importance in heteroepitaxy, describes the dependence of the free energy of magnetic materials on strain/stress. Using our versatile ultrahigh vacuum cantilever beam magnetometer we have investigated the ME constant B2 of epitaxial Fe(001) films in the thickness range of 2–100 nm, where the films are characterised by the magnetisation and the magnetic anisotropy of bulk Fe. Similar to B1 both the magnitude and sign of B2 depend on the film stress. B2 decreases linearly with increasing stress and changes its sign at ca. 4 GPa. For stress-free Fe(001) films the bulk value of B2 is obtained.