Unmagnetized

Unmagnetized describes a state in which a material has no net magnetic moment or macroscopic magnetization. In practice, it means the material is not in a magnetized state and does not retain a persistent magnetic moment when no external magnetic field is present. This can occur when magnetic domains within a ferromagnetic material are oriented randomly, so their individual moments cancel each other out, or in materials that do not exhibit spontaneous magnetization (such as paramagnets or diamagnets) where any magnetization is only induced by an external field.

In ferromagnetic materials, magnetization arises from aligned magnetic domains. An unmagnetized piece typically has undergone demagnetization or heating above its Curie temperature, which randomizes domain orientation and reduces the net moment to near zero. Demagnetization can also be achieved by applying an external magnetic field that is gradually and repeatedly reversed in direction or through mechanical shocks and alternating fields of decreasing intensity.

Measurement of magnetization is usually described by the magnetization vector M or the remanent flux density Br. An unmagnetized state corresponds to M ≈ 0 and Br ≈ 0 at zero external field. Some materials can retain residual magnetization (remanence) after exposure to a strong field, making perfect unmagnetization difficult without deliberate demagnetization.

The term unmagnetized is often used in practical contexts to distinguish objects or samples with negligible stray magnetic fields from those that are magnetized or permanently magnetized. It is not a formal thermodynamic phase but a functional description of the material’s magnetic state at zero field.