Both $\mathrm{Cu}$ and $\mathrm{Fe}$ metals, with face-centered cubic (fcc) crystal structures, are nonmagnetic. However, the substitution of $\mathrm{Cu}$ atoms by Fe in the fcc-$\mathrm{Cu}$ lattice leads to the formation of a random solid solution and the appearance of ferromagnetic order, with a value of the magnetic moment per $\mathrm{Fe}$ atom in a fcc environment even above $2{\mu }_B$. This striking behavior is closely related to magnetovolume effects (Invar), which we have detected by means of lattice thermal expansion and magnetization measurements in $\mathrm{FeCu}$ alloys.

• Received 31 March 2004

DOI:https://doi.org/10.1103/PhysRevB.69.214421