Abstract
The Invar effect has been observed in many Fe rich alloys, most famously Ni Invar.
Generally the Invar behavior is associated with the strong coupling between the lattice
and magnetic degrees of freedom, and therefore depends on the magnetic ordering in
these alloys.
Recent experimental works observed an Invar effect in fcc-FeCu solid solutions.
In the present paper the magnetic states of fcc-FeCu solid solutions for various concentrations
is investigated.
The first principles calculations employ the locally selfconsistent multiple scattering (LSMS) real space method for solving the
LDA Kohn-Sham equation to investigate the non collinear ordering of magnetic moments.
The magnetic order for the low iron concentration is fount to be non-collinear, spin glass like,
and the ferromagnetic order is not stable, whereas for the iron rich alloys for
the ground state equilibrium lattice constants a magnetic order with parallel
aligned Fe moments is stable. In this configuration the induced moments at the Cu
sites order nontrivially on a cone with an opening of approximately 40 degrees
around the Fe moment direction.
