# Publication Citation: "Negative resistance" errors in four-point measurements of crossed-wire devices

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Author(s): Joshua M. Pomeroy; Holger Grube; "Negative resistance" errors in four-point measurements of crossed-wire devices May 01, 2009 "Negative resistance" errors due to non-uniform current distributions significantly distort the apparent electronic performance of devices formed with crossed wires, demonstrated here by resistance, magneto-resistance, current-voltage and variable temperature measurements with and without corrections. Crossed wire devices are frequently used in research settings for exploratory systems or rapid process recipe evolution due to the ease of depositing complete devices {\em in situ} through shadows masks. Unfortunately, this geometry suffers from a negative resistance'' effect that dominates the measurement when the device resistance is remotely similar to or less than the electrode's resistance. In this paper, we using a finite-element model and experimental data to extend work (by others) to illustrate additional errors when 1) devices are not square in shape 2) when the two wires are not the same resistivity, and 3) when the junction resistance is nonlinear in voltage. Using this knowledge and pre-existing analytical work, a straightforward method for correcting experimental measurments is suggested and evaluated. Finally, we illustrate the importance of correcting the data in magneto-resistance, current-voltage and temperature dependent transport measurements to extract the correct physical interpretation. Journal of Applied Physics 105 9 8 pp. magnetic tunnel junction, magnetoresistance, finite element model Condensed Matter Physics