Magnetic properties of the rare-earth-doped semiconductor GaEuN

摘要

Magnetic properties of the rare-earth-doped Ⅲ-nitride semiconductor Ga_(1-x)Eu_xN (x = 0.02) were studied together with X-ray absorption fine structure (XAFS) measurements. Experimental results show that the GaEuN layer is not only paramagnetic originating from the non-magnetic ~7F_0 ground level of trivalent Eu ions, but exhibits also ferromagnetic-like behaviour with easy axis perpendicular to the sample plane. This ferromagnetic component seen also at 300 K seems to be related to divalent Eu ions. The observed magnetic behaviour was also studied theoretically, by introducing a c-axis oriented molecular-field term that acts via the spin-polarized valence band of GaN. This result suggests that Eu ions interact with other Eu ions through the RKKY-type interaction.