Not all metals are magnetic. Most metals do not exhibit the strong magnetic attraction typically associated with a refrigerator magnet. Magnetism exists on a spectrum, and a metal’s response to a magnetic field depends entirely on its atomic structure. Only a select group of metallic elements display powerful, lasting attraction, while the vast majority show either a weak attraction or a slight repulsion when exposed to a magnetic field. This varied response categorizes materials into three main types of magnetic behavior.
The Atomic Origins of Magnetism
The fundamental source of all magnetism lies in the behavior of electrons within an atom. Every electron possesses “spin,” which makes it behave like a microscopic, spinning charged particle, generating a tiny magnetic field and giving the electron a magnetic dipole moment. In most atoms, electrons exist in pairs, and their opposing spins perfectly cancel out, resulting in no net magnetic field. Magnetism only emerges when an atom has unpaired electrons whose magnetic moments do not cancel out, such as in transition metals like iron. These atoms form microscopic regions called magnetic domains where neighboring atoms spontaneously align their moments, though in an unmagnetized metal, these domains point in random directions and cancel out.
The Few Metals That Stick: Ferromagnetism
The strong attraction associated with magnets is ferromagnetism, the most intense form of magnetism. This property is exclusive to a small number of elements, primarily iron (Fe), nickel (Ni), and cobalt (Co), plus a few rare-earth metals. Ferromagnetism is the only type of magnetism powerful enough to retain magnetic properties after an external field is removed, allowing these materials to become permanent magnets. The ability to become strongly magnetic stems from the unique interaction between their magnetic domains. When an external magnetic field is applied, the domains shift and align themselves with the field, creating a powerful, macroscopic magnetic field. Alloys containing these elements, such as steel, inherit this strong magnetic property.
Why Most Metals Are Not Magnetic
Most metals lack the atomic structure necessary to sustain the permanent domain alignment that defines ferromagnetism. These non-ferromagnetic metals fall into two main categories: paramagnetic and diamagnetic, both exhibiting only very weak responses to a magnetic field.
Paramagnetic Metals
Paramagnetic metals, such as aluminum, platinum, and magnesium, have some unpaired electrons, giving their atoms a net magnetic moment. When an external magnetic field is applied, these individual atomic moments momentarily align with the field, causing a slight, temporary attraction. Thermal energy quickly disrupts this weak alignment, and the metal loses all magnetization the moment the external field is removed.
Diamagnetic Metals
Diamagnetic metals, which include copper, gold, silver, and bismuth, have all their electrons paired, meaning their atoms have no permanent magnetic moment. When exposed to an external magnetic field, the motion of their electrons is subtly altered, which induces a temporary magnetic field that weakly opposes the external field. This results in a slight repulsion. Though all materials exhibit a degree of diamagnetism, it is only noticeable in metals where stronger effects are absent.