Extraordinary magnetoresistance in externally shunted van der Pauw plates

We show that extraordinary magnetoresistance (EMR) exhibited by a composite van der Pauw (vdP) disk consisting of a semiconductor with an internal shunt can also be obtained from an electrically equivalent, externally shunted structure that is amenable to fabrication in the mesoscopic sizes required for important magnetic sensor applications. As an example, we use bilinear conformal mapping to transform the composite vdP disk into an externally shunted rectangular plate and calculate its EMR by solving Laplace's equation with appropriate boundary conditions using no adjustable parameters. The calculations are in good agreement with measurements of InSb plates with Au shunts. Room-temperature EMR values as high as 550% at 0.05 T are obtained. (C) 2001 American Institute of Physics.