Hall Field-Sweep Lab — single point vs reversal vs slope fit

Synthetic Hall data for an n-type sample: transverse voltage vs magnetic field, contaminated by a misalignment offset and noise. Three extraction methods compete to recover the true carrier density — watch the single-point shortcut lose as the offset grows.

True carrier density: 1.0×10¹⁶ cm⁻³

Misalignment offset: 30 μV

Presets:

n (single point, +1 T)

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n (±B reversal pair)

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n (slope fit, full sweep)

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Protocol check

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Model honesty: synthetic single-carrier n-type data with V_H = IB/(nqt), I = 1 mA, thickness t = 500 μm, Hall scattering factor r_H = 1, swept over B = −1…+1 T in 21 points with Gaussian voltage noise of 2 μV. The sample is n-type: under the stated lead convention the true Hall slope is negative (electron-like), and the densities in the read-outs are magnitudes — a single-point reading corrupted by a large positive offset can even report the wrong carrier sign. Each preset uses a fixed noise seed so its numbers reproduce exactly; the Regenerate button draws a fresh random realization. The misalignment offset is modelled as field-independent — the leading-order truth; real misalignment also carries a weak even-in-B magnetoresistance component and slow thermoelectric drifts, which is why the full (±I, ±B) reversal ritual described in the article remains the publication standard beyond what this teaching model simulates. Percentages in the read-outs are deviations from the set true density. All values are illustrative teaching quantities, not data for any real material.