Why Magnetoresistance Needs a Model
Magnetoresistance shows how resistance changes when a magnetic field is applied. Susceptibility shows how strongly a material magnetizes under a field. They are related in some materials, but they are not the same measurement. A direct conversion is usually not possible without a calibration model. This calculator uses a practical empirical model, so the result should be treated as an apparent susceptibility.
What the Calculator Estimates
The page first finds magnetoresistance from zero field resistance and field resistance. It then uses the selected field and a calibration constant to estimate apparent susceptibility. The constant represents sample geometry, carrier scattering, domains, and instrument scaling. You can also enter a demagnetizing factor. That correction is useful when shape affects the internal field. Long rods, thin sheets, and compact blocks can behave differently.
Electrical Use Cases
This tool helps compare lab samples, sensor materials, magnetoresistive devices, and quality checks. It is useful when you already have resistance data. It can also estimate mobility from the simple low field relation. The mobility result is a rough check. It does not replace Hall measurements or full magnetic testing.
Input Quality Matters
Small contact errors can distort magnetoresistance. Lead resistance can also shift low ohm readings. Use four wire measurements when possible. Repeat each field point after returning to zero field. Record temperature drift during the run. Clean data makes the inferred susceptibility more meaningful and easier to compare.
Limits and Good Practice
Use measured values from the same temperature and sample orientation. Keep the magnetic field unit consistent. Avoid using noisy resistance values near zero. For ferromagnetic samples, hysteresis can make one field point misleading. For anisotropic materials, rotate the sample and record each orientation. Enter a calibration constant from standards when possible. Without calibration, the value is only a model based estimate.
Reading the Result
A positive magnetoresistance means resistance increased in field. A negative value means resistance decreased. The susceptibility sign reported by the model follows that change. The corrected value adjusts for sample shape. Compare it with Curie Weiss susceptibility when temperature data is available. If both estimates are close, your model may be reasonable. If they differ widely, check units, field strength, contacts, and sample history.