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The authors have investigated the structural and magnetic properties of CrN films grown on MgO(001) and sapphire(0001) by rf-plasma-assisted molecular beam epitaxy. CrN∕MgO(001) exhibits a better epitaxial quality than CrN/sapphire(0001). The CrN∕MgO film shows clear paramagnetic behavior at low temperatures, whereas CrN/sapphire exhibits a ferromagneticlike response with an order temperature above room temperature which resembles the magnetic behavior found in Cr-doped dilute magnetic semiconductors. Keeping in mind that bulk CrN exhibits antiferromagnetic behavior, the dramatically different magnetic behaviors found in epitaxial CrN films grown on MgO and sapphire demonstrate the importance of epitaxial constraints in determining their magnetic properties.

We present structural and magnetic characterization of Cr-doped InN films grown by plasma-assisted molecular beam epitaxy on c-plane sapphire substrates. Low-temperature GaN buffer layers grown by metalorganic vapor-phase epitaxy were used to accommodate the large lattice mismatch between InN and sapphire. A high n-type carrier concentration of 1.5×1020cm−3 was measured in InN films with 3% Cr doping. Films of this type, with high structural perfection, as measured in situ, with reflection high-energy electron diffraction, exhibit a well-defined in-plane magnetic hysteresis loop for temperatures varying from 5to300K. Thus, we show evidence of magnetic order in Cr-doped InN.

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