Flexible test system for measurement of magnetoresistance in ferromagnetic films

A simple, yet versatile magnetoresistance (MR) measurement tester is described. Details of system operation and examples of measurement capability are discussed. The system was designed to measure magnetoresistance on a variety of samples ranging from patterned films on magnetic and nonmagnetic substrates to completed shielded MR heads using readily available standard instrumentation. Data presentation includes plots of magnetoresistance vs. applied field, the derivative of magnetoresistance, and numerical analysis of information from the curve such as hysteresis, dR_max, H_c, bias field, maximum gradient dR/dH, and Barkhausen noise. High speed capture of MR curve data reduces thermal drift problems. Export of data in standard formats allows further analysis on the PC