Abstract
The in-plane aligned MnAs nanowires have been grown by molecular-beam epitaxy on GaAs(001) substrates at high growth temperature ( ≥450 °C). A discontinuous growth with break intervals (50 s' interval per 10 s' growth) was employed. The obtained nanowires were identified to be mainly type-B hexagonal MnAs. The influences of growth temperature and As 4 /Mn flux ratio on the nanowires' morphology were investigated. Both high growth temperature and high As 4 /Mn flux ratio are necessary for the growth of uniaxially aligned MnAs nanowires with high aspect ratio. The magnetic anisotropy of the nanowires and their multimodal size distributions contribute to the large coercivity and special shape of the M-H loops along the magnetic easy axis, which is [11̄02] MnAs [110] GaAs. However, the longer growth time would lead to the both azimuthal alignments of the MnAs wires and the weakening of the magnetic anisotropy. © 2010 American Institute of Physics.