Magnitude and sign control of lithography-induced uniaxial anisotropy in ultra-thin (Ga,Mn)As wires

We were able to control the magnitude and sign of the uniaxial anisotropy in 5-nm-thin (Ga,Mn)As wires by changing the crystallographic direction of the lithography-induced strain relaxation. The 1-mu m-wide (Ga,Mn)As wires, oriented in [110] and [1 (1) over bar0] directions, were fabricated using electron beam lithography. Their magnetic anisotropies were studied by a coherent rotation method at temperatures between 4.5 and 75 K. Depending on the orientation of the wire, the additional uniaxial anisotropy observed along the axis of the 1-mu m-wide samples either increased or decreased the total uniaxial anisotropy. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556556]