Olivines are common minerals that have magnetic and electrical properties useful for many applications. For example, olivines can be durable cathodes that improve the safety of lithium-ion batteries. However, these materials are magnetic only at very low temperatures (below -200° Fahrenheit). This makes it hard to use them in common applications. Scientists have found a way to tune the magnetic properties and raise the magnetic transition temperature of olivine phosphate. The solution is to remove some of the material’s lithium. Neutron studies reveal that the mineral’s chemistry begins to transition to magnetic at higher temperatures as the amount of lithium decreases. This discovery in olivines might be evidence of the long-sought fourth ferroic order, ferrotoroidicity.
Ferroics in physics involves materials that have properties that change under certain conditions. For example, ferromagnetic materials become magnetic when exposed to an external magnetic field. Multiferroics are materials with coupled magnetic and electrical properties that exhibit spontaneous positive/negative polarity. They offer an efficient way to control magnetism by using electric fields or to control electrical polarization by using magnetic fields. Ferroic materials have previously enabled important technologies. These include permanent magnets, capacitors, and shape-memory materials such as cardiovascular stents. Ferrotoroidicity is a theorized form of ferroics. It involves materials whose magnetic domains are switched when exposed to external magnetic fields. Magnetic domains are parts of a material where the atoms’ magnetic fields are aligned and grouped together. Researchers believe that ferrotoroidicity features magnetic vortices, or magnetic whirlpools. The direction that these vortices rotate could likely be changed using electrical fields. This could lead to a new way to store and retrieve electronic data. A clockwise rotation could represent the binary number “0” and a counterclockwise rotation could represent a binary “1.”
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