Nearest-neighbor Mn antiferromagnetic exchange in Ga1−xMnxN

S. Granville,1,2,* B. J. Ruck,2 F. Budde,2 H. J. Trodahl,2 and G. V. M. Williams3 

1 IPMC, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland

2 The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University, P.O. Box 600, Wellington 6140, New Zealand

3Industrial Research Limited, P.O. Box 31310, Lower Hutt 5040, New Zealand


Received 18 November 2009; revised manuscript received 8 April 2010; published 20 May 2010


Abstract:

We analyze the magnetic behavior of well-characterized, precipitate-free Ga1−xMnxN thin films containing Mn at higher levels than previously attained; up to x=0.36. This level is above the percolation threshold xc for nearest-neighbor cations, such that exchange between nearest neighbors will dominate the magnetic response. The susceptibility decreases as the Mn content increases up to and beyond xc, as an increasing fraction of the Mn experiences antiferromagnetic exchange. The dominance of antiferromagnetic behavior at higher Mn concentrations and the total lack of evidence for ferromagnetic ordering even above xc demonstrates that the nature of the exchange between Mn2+ ions in GaN is antiferromagnetic.


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