Formulation
Magnetoresistance is dependence of the electrical resistance of the sample on the strength of external magnetic field. Numerically, it is characterized by the value
where R(H) is the resistance of the sample in a magnetic field H, and R(0) corresponds to H = 0. Alternative forms of this expression may use electrical resistivity instead of resistance, different sign of ΔH, and are sometimes normalized by R(0) rather than R(H).
The term "giant magnetoresistance" indicates that the value ΔH for multilayer structures significantly exceeds the anisotropic magnetoresistance, which has a typical value within a few percent.
Read more about this topic: Giant Magnetoresistance
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