this post was submitted on 19 Dec 2024
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This article is a mess and badly written.
Basicly magnetism comes from electron spin orientation. There are two well known spin configurations.
Ferromagnetism: there is at least one electron with a spin that isn't paired with an opposite spin electron. That atom then has a north and south magnetic pole. Like iron. Arrange all the atoms pointing the same way and you have a refrigerator magnet.
antiferromagnetism: all the electrons in the atom are paired with an opposite spin election. It's complicated but basically they couple together and there isn't a magnetic pole outside the atom. Like in copper.
Altermagnetism: what this article is about. You have a crystal of atoms with an unpaired electrons. The crystal would normally be ferromanetic. However they are arranged in a regular set of pairs that cause the electron spin to cancle out. Think of a checkerboard pattern where each white square cancels a black square next to it.
The antiferromagnetism and altermagnetism both have the spins cancelled out but the mechanism is different so there are different properties. Kramers degenerate vs wavevector.
In theory this gives you an extra state spin. So a magnetic drive uses a pattern of north and south to encode information. Ie NNSN becomes 0010.
With this you have north, south but also spin left, right. So you can encode more information.
How do you control the spin of an electron?
I know the usual way uses oscillating magnetic fields and it being very cold. There are other ways i'm not familiar with. I'm a classical computer engineer not a quantum computer engineer. I'm more used to energy bandgap then spin control.
Interesting… so like, if one were to use it on magnetic storage, you’d theoretically be able to work in quaternary?
Yup
While it is true Kramer outed himself as a degenerate at the smile factory in philadelphia I don't believe this is an appropriate place to bring it up.
Sorta like linear vs. circular polarization in radio transmissions?
In the sense that it's two different but similar states.
I'm pretty sure we can say it's not actually spin now. Electrons have a charge and a magnetic field. If they are charged and spinning that world generate a magnetic field. So spin was used to describe the orientation of the field. The name for the state stuck
you seem knowledgeable on this topic. Enough that I hope you could answer my questions.
with this new state, would it make it easier/possible to improve not just efficiency but throughput of permanent magnetic motors?
also, you mentioned the programmability of magnets. would this allow us to build more "task specific" electric motors? for example; a motor with high torque at low rpms and low torque at high rpms?
This is a bit outside my field. That said I don't think so.
The overall crystal should be very weakly magnetic. You want strong magnet with a high flux density so the electric field can push or pull against it.
I think this would be more useful in quantum computing as you get two bits polarity and spin. Or high density storage.
But who knows. There are clever physicists out there that know a lot more about this. They presumably see many more possibilities then I do. If the effect can be interrupted you could stitch between states. Like turning a magnet on and off. That would have uses like you described.
Thank you. That was explained very well!