Magnetic behavior of Gd-doped GaN nanoceramics

The magnetic properties of GaN:2%Gd nanopowder and GaN:2%Gd nanoceramics, prepared by low-temperature high-pressure (LTHP) method, were studied in wide ranges of temperature (1.72-400 K) and magnetic field (up to 5 T). Whereas the powder was found to exhibit regular Curie-Weiss behavior of the magnetic susceptibility, due to the presence of Gd3+ ions, the nanoceramics showed quite unusual properties with the effective magnetic moment and the low-temperature magnetization measured in strong magnetic fields being strongly reduced with respect to the theoretical values. The observed magnitude of the paramagnetic Curie temperature as well as the low-temperature upturns in the magnetic susceptibility seem indicate development in the nanoceramics of magnetic exchange interactions between the magnetic moments carried by the Gd ions. (C) 2007 Elsevier B.V. All rights reserved.