Nonferromagnets

Nonferromagnets are materials that do not exhibit ferromagnetic order, meaning they do not develop a spontaneous net magnetization in zero external field. While they lack ferromagnetism, many nonferromagnets display other magnetic behaviors, such as diamagnetism, paramagnetism, or various forms of magnetic order that do not produce a permanent, large-scale magnetization.

Diamagnetic materials generate a weak, negative magnetization that opposes an applied magnetic field and do not retain magnetization when the field is removed. This response is generally small and universal across many substances. Paramagnetic materials have unpaired electron spins that align partially with an external field, producing a positive susceptibility. They show no spontaneous magnetization at zero field and typically follow Curie or Curie-Weiss temperature dependence, with susceptibility decreasing as temperature rises.

Antiferromagnetic materials host an ordered arrangement in which neighboring magnetic moments align antiparallel, canceling the net moment at zero field. They can exhibit characteristic changes in magnetic susceptibility near the Néel temperature, below which the antiferromagnetic order is established. Some materials also show weak canting or other complexities that yield small residual moments, but these are not true ferromagnetism.

In classification schemes, ferrimagnetic materials—where sublattices carry unequal opposite moments—often present a net magnetization and are commonly treated as ferromagnetic in many contexts. Nonferromagnets thus encompass diamagnets, paramagnets, antiferromagnets, and other systems lacking spontaneous ferromagnetic order.

Examples include graphite and bismuth (diamagnetic), copper and aluminum (paramagnetic), and certain oxide and sulfide crystals that order antiferromagnetically at low temperatures. Nonferromagnets play a key role as substrates, in exchange bias research, and in studies of fundamental magnetic phase transitions.