STRUCTURE OF Er | Y SUPERLATTICES

The magnetic structure of Er | Y superlattices has been determined by neutron diffraction and squid magnetometry on single crystal samples grown on sapphire substrates by molecular-beam-epitaxy techniques. The turn angle in the Er layers is magneto-elastically "clamped", and in fact locks-in to the commensurate state ω = 2π / 7 below about 35 K. For the [Er13 | Y26] superlattice the low temperature state is not 2π / 7 but can be shifted to that value by a magnetic field, since this state has a net moment of 8 µB / 7 atoms along the c-axis