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 $1-μm$-wide (Ga,Mn)As wires, oriented in [110] and $[11¯0]$ 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 $1-μm$-wide samples either increased or decreased the total uniaxial anisotropy.