Ultrathin materials made of a single layer of atoms have riveted scientists' attention since the discovery of the first such material—graphene—about 17 years ago. Among other advances since then, researchers including those from a pioneering lab at MIT have found that stacking individual sheets of the 2D materials, and sometimes twisting them at a slight angle to each other, can give them new properties, from superconductivity to magnetism.
Now MIT physicists from the same lab and colleagues have done just that with boron nitride, known as "white graphene" in part because it has an atomic structure similar to its famous cousin. The team has shown that when two single sheets of boron nitride are stacked parallel to each other, the material becomes ferroelectric, in which positive and negative charges in the material spontaneously head to different sides, or poles. Upon the application of an external electric field, those charges switch sides, reversing the polarization. Importantly, all of this happens at room temperature.
The new material, which works via a mechanism that is completely different from existing ferroelectric materials, could have many applications.
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