A magnetic phase is a distinct state in which the atomic magnetic moments of a material organize. Some materials can change magnetic phases; e.g. heat iron past 770° and it loses it’s ability to be a magnet. Cool it back down and it’s ferromagnetic properties return. It literally changes magnetic phases.
There are (until recently) two phases of magnetism: ferromagnetic and antiferromagnetic. The other poster who replied said “dia and para”; their heart is in the right place, but their response is entirely incorrect.
Until now, there were two known magnetic phases: ferromagnetic and antiferromagnetic.
The best analogy I’ve seen, though significantly over-simplified, is a great way to visualize the basics magnetic phases. Think of any given material as being a highway, and the electromagnetic energy within that material as two types of cars: blue cars and orange cars. It may be useful to think of the highway as a “North/South” highway, as in magnetic poles, but again, that is a significant oversimplification, and only meant as an illustration, not an explanation of what is actually happening within the material at a quantum level.
A ferromagnetic “highway” is basically a one-way road; the conditions of the road only allow blue cars to move in a single direction, no other color or direction of travel is allowed. This phase attracts only blue cars moving in one direction, and repels orange cars, as well as blue cars moving in the opposing direction. This type of “highway” is what creates what we commonly know as magnetism.
An antiferromagnetic “highway” allows both colors to travel equally in both directions; this phase of motion has an equal amount of force in both directions regardless of a car’s direction or color, and so this type of “highway” is what we would find in non-magnetic materials.
The new phase of magnetism is called altermagnetism. In a conventional antiferromagnet, both kinds of cars generally experience the same road conditions. In an altermagnet, the roads effectively favor different kinds of cars depending on which direction they travel. Travel along one direction, and the blue cars might be favored. Travel along another, and the orange cars might be favored. Importantly, neither kind of car dominates the entire road.
That’s the unusual feature of altermagnetism: the car’s behavior depends on direction, even though the material has no net magnetization.
You are correct, but since some may read that and assume that all aviation fuel is leaded, I wanted to add more info.
Most people don’t know that “airplane fuel” and “jet fuel” are different. Jet fuel is not leaded. The fuel used by small, piston-driven prop engines is. Because small piston aircraft still use leaded fuel, aviation is still the largest source of airborne lead emissions. The FAA is working to phase it out by 2030.
The danger from leaded fuels don’t come from handling, but from the exhaust. The lead becomes breathable and enters the environment, exposing those who lived in urban areas and near roads to more lead than others.
The other poster isn’t wrong about airplane fuel being leaded, but that can be misleading because most people don’t know that “airplane fuel” and “jet fuel” are different. Jet fuel is not leaded, but the fuel used by small, piston-driven prop engines is.
We are still working to fully understand how all of the fundamental forces emerge from their respective fields, so there’s still a lot that we don’t yet know about how magnetism works. Even top researchers feel like they’re missing part of the concept 😅
In the analogy, the blue and orange cars represent magnetic moments (spin) of electrons. I want to emphasize that the analogy hand-waves a lot of what is actually happening in the material in favor of simplicity.