A magnet creates an invisible magnetic field, which exerts a force on moving electric charges and magnetic materials. This field is generated by the motion of electrons within the atoms of the material. While all matter interacts with a magnetic field, only a select group of metals demonstrates the strong, noticeable attraction most people associate with magnetism. This unique attraction is due to the specific atomic structure of these elements, which is governed by quantum physics.
Identifying the Strongly Magnetic Metals
The phenomenon of strong magnetic attraction is scientifically known as ferromagnetism, a property exhibited by very few elements at room temperature. The three primary elemental metals that are strongly attracted to a magnet are iron (Fe), nickel (Ni), and cobalt (Co). These distinct transition metals possess the intense magnetic property that makes them the foundation for nearly all industrial and household magnetic applications.
These metals can be turned into permanent magnets or temporarily magnetized by an external field. Many alloys also retain this property, such as steel, which is an alloy of iron and carbon. Modern permanent magnets are often made from alloys combining these elements with rare-earth metals, such as neodymium-iron-boron or samarium-cobalt, to maximize the ferromagnetic effect.
The Physics Behind Strong Magnetic Attraction
Magnetic attraction begins at the atomic level with the movement of electrons. Every electron behaves like a tiny magnet due to electron spin. In most materials, electrons are paired up, and the magnetic moment created by one spinning electron is canceled out by its partner spinning in the opposite direction.
Ferromagnetic elements possess unpaired electrons, meaning their magnetic moments do not cancel out, resulting in a net magnetic moment for each atom. These individual atomic magnetic moments spontaneously align themselves parallel within microscopic regions known as magnetic domains.
Within a single domain, the magnetic field is intense because all the atomic spins point in the same direction. In an unmagnetized metal, the domains are oriented randomly, causing their magnetic fields to cancel each other out, resulting in no overall magnetic field. When an external magnet is brought near, the magnetic field exerts a torque that causes the domain walls to shift, forcing the individual domains to rotate and align with the external field. This alignment of already-magnetized domains creates the powerful force of attraction.
Why Most Metals Do Not Attract Magnets
Most metals, including common ones like aluminum, copper, gold, and silver, are not ferromagnetic and are not noticeably attracted to a magnet. These materials still interact with magnetic fields, but their response falls into two much weaker categories: paramagnetism and diamagnetism. The resulting force is so slight that it can only be measured with sensitive laboratory equipment.
Paramagnetic metals, such as aluminum, contain atoms with unpaired electrons that create small, temporary magnetic moments. When exposed to an external magnetic field, these moments weakly align with the field, resulting in a slight attraction. Unlike ferromagnetic materials, the magnetic moments in paramagnets become randomly oriented again as soon as the external field is removed due to thermal energy, meaning they cannot become permanent magnets.
Diamagnetic metals, which include copper and gold, have atoms where all electrons are paired, resulting in no permanent magnetic moment. When a magnetic field is applied, it induces a tiny magnetic moment that opposes the external field, causing a weak force of repulsion. Since diamagnetism is a property inherent to all matter, paramagnetism is only slightly stronger.