Interaction of multiple iron balls in magnetic fields

We have measured the field distribution around multiple iron balls exposed to nearly parallel magnetic fields generated from a large permanent magnet. It has been found that all the balls are magnetized in the same direction, which causes repulsive interaction among them. Such a repulsive interaction between magnetized sphere iron balls results in peculiar distributions of the iron balls, in that the balls are separated each other, and those sitting in the second row and the third row could be suspended in midair when they are packed in a plastic box. A group of floating balls could jointly be transported by rotating the lifting magnet.