“How can we create a one-sided magnet?
We have a problem. Suppose that we want to create a magnet, but with one very simple yet very difficult constraint, we want the magnetic field to be only present on one side.
Now that we have decided on the requirements, let’s use our engineering abilities to bring this idea into reality. Our main problem is that magnets fields are usually symmetric on both sides because the polarity of the entire material points in the same direction. Now, how can we get around this physical phenomena to acheive our goals? Well, luckily for us, there is another facet of magnets that could be quite cordial to our goal if applied correctly. If two magnetic fields interact with eachother and go in oppossite direction, then there would be a cancellation of force. Now, what if instead of having one continuous material with each part having the same magnetic direction, we were to fasten discrete blocks together, with each the polarity of each block being 90 degrees perpendicular to the block before it? With this method, the magnetic fields on one side of the blocks would cancel out while the fields on the opposite side would super-combine, giving us a nearly one sided magnet if the this pattern repeats. Scientist and Engineers have termed this type of arrangement a hallbach array. Believe it or not, you probably see hallbach arrays everytime time in the morning, as hallbach arrays are what what makes refridgerator magnets work!