Making mini-magnets that induce a quantum anomalous Hall effect

A new device has been fabricated that can demonstrate the quantum anomalous Hall effect, in which tiny, discrete voltage steps are generated by an external magnetic field. This work may enable extremely low-power electronics, ...

Magnetic surprise revealed in 'magic-angle' graphene

When two sheets of the carbon nanomaterial graphene are stacked together at a particular angle with respect to each other, it gives rise to some fascinating physics. For instance, when this so-called "magic-angle graphene" ...

Energy harvesting technology based on ferromagnetic resonance

Researchers from the Graduate School of Engineering, Osaka City University have succeeded in storing electricity with the voltage generated from the conversion phenomenon of ferromagnetic resonance (FMR) using an ultra-thin ...

Spintronics: Improving electronics with finer spin control

Spintronics is an emerging technology for manufacturing electronic devices that take advantage of electron spin and its associated magnetic properties, instead of using the electrical charge of an electron, to carry information. ...

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Ferromagnetism

Ferromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished. Ferromagnetism (including ferrimagnetism) is the strongest type; it is the only type that creates forces strong enough to be felt, and is responsible for the common phenomena of magnetism encountered in everyday life. Other substances respond weakly to magnetic fields with two other types of magnetism, paramagnetism and diamagnetism, but the forces are so weak that they can only be detected by sensitive instruments in a laboratory. An everyday example of ferromagnetism is a refrigerator magnet used to hold notes on a refrigerator door. The attraction between a magnet and ferromagnetic material is "the quality of magnetism first apparent to the ancient world, and to us today".

Permanent magnets (materials that can be magnetized by an external magnetic field and remain magnetized after the external field is removed) are either ferromagnetic or ferrimagnetic, as are other materials that are noticeably attracted to them. Only a few substances are ferromagnetic; the common ones are iron, nickel, cobalt and their alloys, some compounds of rare earth metals, and a few naturally-occurring minerals such as lodestone.

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