Paramagnetism (opens in new tab) occurs when a material becomes magnetic temporarily when placed in a magnetic field and reverts to its nonmagnetic state as soon as the external field is removed. (In theory, because of their mutual repulsion, one can be levitated above the other.) Certain superconducting materials show even stronger diamagnetism below their critical temperature (the temperature at which they become superconducting) and so rare-earth magnets can be levitated above them. Pyrolytic carbon, a substance similar to graphite, shows even stronger diamagnetism than bismuth, albeit only along one axis, and can actually be levitated above a super-strong rare earth magnet. There are, however, some notable exceptions. This causes all materials to be repelled by a permanent magnet however, the resulting force is usually too weak to be noticeable. When an external magnetic field is applied to a material, these current loops tend to align in such a way as to oppose the applied field. According to Gerald Küstler, a widely published independent German researcher and inventor, in his paper, "Diamagnetic Levitation - Historical Milestones," (opens in new tab) published in the Romanian Journal of Technical Sciences, Brugnams observed, "Only the dark and almost violet-colored bismuth displayed a particular phenomenon in the study for when I laid a piece of it upon a round sheet of paper floating atop water, it was repelled by both poles of the magnet."ĭiamagnetism is caused by the orbital motion of electrons within atoms creating tiny current loops, which produce weak magnetic fields, according to HyperPhysics (opens in new tab). Anton Brugnams first discovered diamagnetism (opens in new tab) in 1778 while using permanent magnets in his search for materials containing iron. Magnetism takes many other forms, but except for ferromagnetism, they are usually too weak to be observed except by sensitive laboratory instruments or at very low temperatures. These include nickel, cobalt, and some rare earth metals (opens in new tab) such as samarium or neodymium, which are used to make super-strong permanent magnets. Other metals besides iron can have ferromagnetic properties. Thereafter, the magnetic compass became a tremendous aid to navigation, particularly during the day and on nights when the stars were hidden by clouds. 1000, the Chinese discovered that a magnet floating in a bowl of water always lined up in the north-south direction. According to NASA (opens in new tab), around A.D. People soon learned that they could magnetize an iron needle by stroking it with a lodestone, causing a majority of the unpaired electrons in the needle to line up in one direction. While scientists don't know exactly how lodestones form, "most scientists believe that lodestone is magnetite that has been hit by lightning," according to the University of Arizona (opens in new tab). These naturally occurring magnets are called lodestones. Pieces of magnetite can be found scattered on or near the surface of the Earth, and occasionally, one will be magnetized. The prefix "ferro" refers to iron because permanent magnetism was first observed in a form of natural iron ore called magnetite, Fe3O4. Permanent magnets are the result of ferromagnetism (opens in new tab). If the alignment of unpaired electrons persists without the application of an external magnetic field or electric current, it produces a permanent magnet. (Image credit: Aleksandr Pobedimskiy via Shutterstock) Magnetite (also known as lodestone) is the most magnetic of all the naturally-occurring minerals on Earth. When a significant majority of unpaired electrons are aligned with their spins in the same direction, they combine to produce a magnetic field that is strong enough to be observed on a macroscopic scale. The direction of their spin determines the direction of the magnetic field, according to the Non-Destructive Testing (NDT) Resource Center. However, some atoms contain one or more unpaired electrons, and these unpaired electrons create a tiny magnetic field. In this case, the magnetic fields created by those spins point in opposite directions, so they cancel each other. Electrons all have a fundamental quantum mechanical property of angular momentum, known as "spin." Inside atoms, most electrons tend to form pairs in which one of them is "spin up" and the other is "spin down," or in other words their angular momenta point in opposite directions. Magnetic fields are generated by the motion of electric charges, according to HyperPhysics.
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