CaloMag

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Magnetocaloric analysis of PPMS VSM isotherms

Maxwell ΔS_M, Banerjee classification and RCP on one grid, so a mistake in mass or branch appears everywhere at once.

A conventional magnetocaloric reduction is a chain of hand-offs. One skips the PPMS header, splits isotherms, converts emu to emu g⁻¹, interpolates onto a field grid, evaluates ΔS_M, then rebuilds Arrott plots and refrigerant capacity as separate worksheets. Origin and Python will draw what the operator already understands. They do not know that a negative Arrott slope is a first-order warning rather than a fitting glitch.

CaloMag is a dedicated thermodynamic engine for PPMS VSM isotherms. After mass normalisation it treats the isotherm grid as the thermodynamic object, classifies M–H versus M–T from column variation, and evaluates Maxwell ΔS_M, RCP, ΔC_p, Banerjee on Arrott plots, and critical exponents from modified Arrott, Kouvel–Fisher and power-law scaling. Mean-field scaling is flagged, not pretended, on a discontinuous transition.

Iso-field −ΔS_M(T) on the Gd demonstration. The peak sits at T_C, broadens with field, and remains symmetric — the signature of a continuous ferromagnetic transition.

M–H isotherms of the Gd demonstration (250–336 K). Colour encodes temperature. Mass-normalised moment, μ₀H up to 5 T — the same grid from which Maxwell ΔS_M is integrated.

Arrott plot (M² vs H/M) for Gd. All isotherms have positive slope. By the Banerjee criterion the transition is second-order; CaloMag labels the session as such.

What it does

Native MultiVu parse; Time, T, H, M identified; mass normalisation that never overwrites the raw file
Maxwell ΔS_M, FWHM, RCP and ΔC_p = T (∂ΔS_M/∂T)_H on the same grid
Banerjee criterion and MAP / Kouvel–Fisher / power-law exponents with β, γ adjustable
Gd (SOMT) and La(Fe,Si)₁₃ (FOMT) demonstrations so the two working-fluid families can be read side by side
Origin-like figures and a reopenable .calomag.json; data never leave the machine