The effect of multiple B+ implantation on 109 μm square single-domain magneto-optic elements formed by chemical etching of Bi-doped Tm:YIG epitaxial films ( m) is investigated by measuring the external switching field Hswsw required to reverse the magnetization as a function of implant profile, dosage, and the angle θ between the field and the film normal. For low doses (< 0.15% strain), switching is determined by coherent rotation in the implanted layer; Hswdecreases linearly ( ) from Hk. 4πMs= 3995 Oe to 566 Oe and Hsw(θ) is the classic switching curve for a uniaxial anisotropy. For higher doses, Hswremains constant or increases slightly, and Hsw , indicating that switching is limited by wall motion, and the force proportional to at the implant/bulk interface. With annealing Hswincreases for low dose as Hkincreases, and decreases for higher doses as decreases. Measurements width three stain profiles intricate that more gradual strain transitions produce lower Hswdue to decreased .