In some materials, electron spins spontaneously align their direction, leading to the phenomenon of ferromagnetism which is well known e.g. in iron. (sciencedaily.com)
«Interestingly, we found that magnetic anisotropy is an inherent property in the 2 - D material we studied, and because of this characteristic, we were able to detect the intrinsic ferromagnetism,» said study lead author Cheng Gong, a postdoctoral researcher in Zhang's lab. (sciencedaily.com)
Such polarity - reversing materials are called ferroelectric (an analogy with ferromagnetism, even though iron is not involved in the electric version). (sciencenews.org)