Magnetic and chemical aspects of Cr-based films grown on GaAs(001)

We have investigated the magnetic and chemical properties of very thin films of Cr, CrAs, and arsenized Cr, grown by molecular beam epitaxy on GaAs (001), using x-ray photoemission spectroscopy and SQUID magnetometry. The substrate was kept at 200 °C in an As-rich environment for incoming Cr atoms at the GaAs surface. Gallium segregation and the chemical reactivity between Ga and Cr have negligible contribution to the formation of different thin films. A clear ferromagnetic response, even at room temperature, suggests the formation of a very thin buried interfacial layer during the growth process.