Combining 2D magnets and 2D semiconductor material

Amazing stuff! This seems to be another example of humans transcending nature!

"... scientists have shown that two previously separate fields in condensed matter physics can be combined to yield new, exotic phenomena. ...
What might happen if the two fields — 2D magnets and moiré materials — are combined? That is the focus of the current work. ...
Specifically, the team predicts that a structure made of two layers of a 2D magnet topped by a layer of a 2D semiconductor material will generate a phenomenon called a flat band, in which the electrons in the semiconductor stand still. ...

Key to the research is an exotic particle called a skyrmion that involves a property of electrons called spin (another, more familiar property of electrons is their charge). The spin can be thought of as an elementary magnet, in which the electrons in an atom are like little needles orienting in a certain way. ...

In a skyrmion, the spins form knot-like whirls that are distributed across the surface of a material. Importantly, skyrmions are topological objects, or those whose properties do not change even when they are subjected to large deformations. ... The implication is that future applications of skyrmions would be very robust, or difficult to disrupt, perhaps leading to a better form of computer memory storage. ...

team predicts that skyrmions in the 2D magnet layer will “imprint” themselves on the electrons in the semiconductor layer, endowing them with skyrmion-like properties themselves. These properties also stop the movement of the semiconductor’s electrons, resulting in the flat band. ...
In the ... paper, the physicists also define the best conditions for creating a magnet-semiconductor structure with a flat band. ...
that the best combination involves a layer of molybdenum disulfide (the semiconductor) over layers of chromium tribromide (the magnet). ...
The team further identified a certain “magic” level of magnetization that is also key to realizing a strong flat band. ..."

From the abstract (this is a difficult to understand one written for specialists):

"van der Waals (vdW) heterostructures formed by two-dimensional (2D) magnets and semiconductors have provided a fertile ground for fundamental science and spintronics. We present first-principles calculations finding a proximity exchange splitting of 14 meV (equivalent to an effective Zeeman field of 120 T) in the vdW magnet-semiconductor heterostructure MoS 2/CrBr 3, leading to a 2D spin-polarized half-metal with carrier densities ranging up to 1013 cm−2. We consequently explore the effect of large exchange coupling on the electronic band structure when the magnetic layer hosts chiral spin textures such as skyrmions. A flat Chern band is found at a “magic” value of magnetization m¯¯¯¯¯∼0.2

 for Schrödinger electrons, and it generally occurs for Dirac electrons. The magnetic proximity–induced anomalous Hall effect enables transport-based detection of chiral spin textures, and flat Chern bands provide an avenue for engineering various strongly correlated states."

MIT physicists predict exotic new phenomena and give “recipe” for realizing them | MIT News | Massachusetts Institute of Technology Work with skyrmions could have applications in future computers and more.

Giant proximity exchange and flat Chern band in 2D magnet-semiconductor heterostructures (open access)