This is a demo of a spring-latch polymagnet. I’ll talk about what a polymagnet is and how they are made.
First, I’d like to talk about what this thing actually is. This display piece is made up of three different pieces. You first have the central shaft (in brass) that holds the other two pieces. Each of the two pieces (in red) have a magnet on the face pointing to the other piece.
Now, a regular magnet exhibits one of two possible behaviours. If the magnet faces a like pole, it repels. If it faces an opposite pole, it attracts. However, these magnets are different. They repel until you rotate one of them by 180°, which is when they attract. But here’s the thing. [[[Pull them too far apart, and they actually start attracting again.]]]
Now, as you might already guess, these magnets actually have two poles on the same face, which is somewhat unheard of. Usually, a magnet has a pole on one face, and then the opposite pole on the other face. This is a result of how magnets are manufactured.
But polymagnets have both their poles on the same face. In the case of the polymagnet I have, they have the arrangement below:
It is also important to note that the brass shaft serves a purpose. It aligns the axes of the two disks. This ensures that the magnets exhibit the expected behaviour.
So, how do people make these polymagnets? Well, one hint as to how they make them comes from an alternative name for these magnets: Correlated Magnetic Structures. You can think of a polymagnet as many tiny magnets glued together. However, it is a lot more complex than that.
In order to make a polymagnet, you need a device that can “print” a magnetic field onto the raw material. I couldn’t find a detailed piece of work that explains how this works exactly. However, my understanding is that it applies a very powerful, concentrated and controlled magnetic field onto a very tiny area of the to-be magnet (like a pixel). Additionally, the device is able to control the locations of the north and south poles of the to-be magnet.
You can then repeat this process over the entire area of the to-be magnet and generate any pattern you like. The process is fairly intensive, but that is what I could gather from the research that I did.
If you are curious about magnets and how magnetism arises, you can check out a previous collection spotlight on the Magnetic Sand Hourglass. That post talks about how magnetism arises and gives a little more information on magnetism as a whole.