Room temperature ferromagnetism of Ge/MnAs digital alloys

The magnetic properties of Ge/MnAs digital alloys on GaAs (001) substrates, grown by molecular beam epitaxy, were investigated using a Quantum Design SQUID magnetometer. The Ge (1 nm)/MnAs (0.15 nm) digital alloy showed ferromagnetism up to 334 K with a coercive field of 576 Oe at room temperature, as determined from temperature-dependent magnetization and hysteresis loop measurements. The ferromagnetic and antiferromagnetic phases of a Ge7/(Mn0.5As0.5)(1) superlattice, investigated using the full-potential linearized augmented plane wave (FLAPW) method yielded a ferromagnetic ground state with a high spin magnetic moment of Mn (3.45 mu(B)) which induces only very small magnetic moments on its neighboring As or Ge atoms.