September 2017: Dr Jiabao Yi, "Intrinsic and spatially non-uniform ferromagnetism in Co doped ZnO films"
Intrinsic ferromagnetism is required for a diluted magnetic semiconductor (DMS). In this work, Co has successfully substituted Zn site in ZnO based DMS and TEM mapping suggests uniform distribution of Co dopants. However, low energy muon spin relaxation indicates that the total volume of magnetic phase is 70%, suggesting non-uniform ferromagnetism. The result suggests that magnetic polarons may contribute to the ferromagnetism due to the magnetic non-uniformity. The work has shown that structure uniformity is different from magnetic uniformity. The definition of Intrinsic ferromagnetism should be carefully defined.
Read the full article, as published in Physical Review B (Physical Review B 96 (10), 104423 (2017)).