In solid-state magnetism, materials that lack permanent magnetic dipoles (and develop only weak, negative magnetization in an applied field) are classified as which type?

Introduction / Context:Magnetic behavior of materials arises from electron spins and orbital motions. Whether a solid exhibits a net permanent moment depends on the presence of unpaired spins and cooperative ordering. This question checks the basic classification when no permanent dipoles exist in the absence of a field.

Given Data / Assumptions:

• No permanent magnetic dipoles; all atomic or molecular moments cancel out in zero field.
• Consider response in a weak, applied magnetic field.
• Temperature is not driving long-range magnetic order (no ferromagnetic or ferrimagnetic states).

Concept / Approach:Diamagnetic materials have all electrons paired; they exhibit an induced magnetic moment opposite to the external field due to Lenz-like response of orbital motion, giving a small negative susceptibility. Paramagnets have unpaired electrons that align weakly with the field (positive susceptibility) but no permanent magnetization without a field. Ferromagnets and ferrimagnets show spontaneous ordering and domain behavior leading to permanent dipoles.

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