= Solution
In <paramagnetism>, a material develops <magnetization> along a weak applied field, with positive susceptibility; in <diamagnetism>, it develops an induced moment opposing it, with negative susceptibility. In a simple localized-moment paramagnet, Zeeman alignment competes with thermal disorder. For independent two-state moments $\pm\mu$,
$$
Z_1=2\cosh\frac{\mu B}{k_BT},\qquad
M=n\mu\tanh\frac{\mu B}{k_BT},\qquad
\chi_H\simeq\frac{\mu_0n\mu^2}{k_BT}
$$
when the field is weak and demagnetizing corrections are negligible. Stronger fields saturate the moment; interactions and conduction-electron <Pauli paramagnetism> can depart from this <Curie law>.
Ordinary <diamagnetism> comes from a field-induced change of orbital motion, including in closed-shell matter without permanent atomic moments. Its weak susceptibility is often nearly <temperature> independent away from a transition, and it contributes a background even when another magnetic response dominates. A nonuniform field tends to attract a paramagnetic specimen toward stronger field and repel a diamagnetic specimen in the weak linear regime. Calibrate the holder contribution and field <gradient> and measure a <temperature>/field series to distinguish induced response from retained <magnetization>. Ferromagnetic <hysteresis> and superconducting flux expulsion require different collective explanations.
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