Individual magnetic impurities or small collections of magnetic impurities in III-V semiconductors can be identified via scanning tunneling microscopy (STM) [1,2], their exchange interaction can be measured , and they can have remarkably long spin coherence times . Spin-1/2 impurities are able to be addressed individually and the eigenstates tailored allowing the construction of engineered spin networks . We describe an approach to explore the coherent spin dynamics of a spin-1/2 defect coupled to an additional spin-1/2 defect via exchange interaction with a spin-polarized STM contact through low-field magnetoresistance. The inherent anisotropy [2,3,5,6] in conjunction with the applied magnetic field should allow one to describe a single spin Hanle curve. In addition, measurements of the spin coherence time and the local hyperfine interaction should be feasible. This analysis is then used to guide the examination of coherent spin-dynamics involving coupled Mn-hole complexes in III-V semiconductors.
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