Magnets are objects that produce an invisible force field, known as a magnetic field, which can attract or repel other magnetic materials. This fundamental force is responsible for why certain objects stick to magnets while others do not. Understanding which materials interact with magnets involves exploring the atomic structure of different substances.
The Science Behind Attraction
Magnetic attraction originates at the atomic level, from the behavior of electrons within a material. Electrons possess a property called “spin,” which makes each electron a tiny magnet with its own magnetic field. In most materials, electrons are paired, with each electron spinning in an opposite direction, causing their magnetic fields to cancel. These materials exhibit no overall magnetic effect.
However, in certain materials, some electrons remain unpaired, and their individual magnetic fields do not cancel. These atomic magnetic moments tend to align within small regions inside the material, forming magnetic domains. When these domains are randomly oriented, the material is not magnetic. When exposed to an external magnetic field, these domains can align, causing the material to become strongly attracted.
Materials Magnets Attract
Ferromagnetic materials are those strongly attracted to magnets. They can become magnetized themselves and remain so even after the external magnetic field is removed. The most common examples of ferromagnetic elements are iron, nickel, and cobalt. Gadolinium and dysprosium also exhibit ferromagnetism.
Many everyday objects are made from these elements or their alloys. Steel, for instance, is an alloy predominantly made of iron and is attracted to magnets. Some types of stainless steel, particularly those containing sufficient iron, can also be magnetic.
Other examples include Alnico, an alloy of aluminum, nickel, and cobalt used in permanent magnets, and ferrites, ceramic compounds often found in credit card magnetic stripes. Common items that magnets stick to include refrigerator doors, certain coins, and various tools.
Materials Magnets Don’t Attract
Many materials do not exhibit a noticeable attraction to magnets. These are termed non-magnetic materials because their internal atomic structure does not allow for the strong alignment of magnetic moments. In these substances, electron spins are either paired, canceling their magnetic effects, or their atomic magnetic moments are randomly oriented and too weak to respond significantly to an external magnetic field.
Common non-magnetic materials include wood, plastic, glass, and rubber. Many metals are also not strongly attracted to magnets, such as aluminum, copper, brass, gold, silver, lead, zinc, and platinum. While all substances respond weakly to magnetic fields (paramagnetic materials are weakly attracted, and diamagnetic materials are weakly repelled), these effects are too subtle to be observed without specialized equipment. Therefore, for practical purposes, these materials are considered non-magnetic.