X-ray magnetic circular dichroism characterization of GaN /Ga1-xMnxN digital ferromagnetic heterostructure

The authors have investigated the magnetic properties of a Ga_{N /Ga1-x}Mn_xN _{(x=0.1) digital ferromagnetic heterostructure (DFH) showing ferromagnetic behavior using soft x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD). The Mn L2,3-edge XAS spectra were similar to those of Ga1-x}Mn_xN _{random alloy thin films, indicating a substitutional doping of high concentration Mn into GaN. From the XMCD measurements, it was revealed that paramagnetic and ferromagnetic Mn atoms coexisted in the Ga1-x}Mn_xN _{digital layers. Subtle differences were also found from the XMCD spectra between the electronic states of the ferromagnetic and paramagnetic Mn²⁺ ions. The ferromagnetic moment per Mn atom estimated from XMCD agreed well with that estimated from superconducting quantum interference device measurements, indicating that the ferromagnetic behavior of the GaN/Ga1-x}Mn_xN _{DFH sample arises only from substitutional Mn²⁺ ions in the Ga1-x}Mn_xN digital layers and not from ferromagnetic precipitates.