It's all about the magnetic surfaces. Some pictures: https://images.slideplayer.com/33/10482660/slides/slide_9.jpg https://images.slideplayer.com/33/10482660/s

It's all about the magnetic surfaces. Some pictures: https://images.slideplayer.com/33/10482660/slides/slide_9.jpg https://images.slideplayer.com/33/10482660/slides/slide_9.jp... https://www.nature.com/articles/ncomms13493/figures/1 https://www.nature.com/articles/ncomms13493/figures/1 https://imgur.com/gallery/eikBLMX https://imgur.com/gallery/eikBLMX