October 2020

Researchers from Rice University and Texas A&M University have discovered that a 2D derivative of perovskite has a good potential for valleytronics applications.

The researchers synthesized a layered compound of cesium, bismuth and iodine that is able to store the valley states of electrons, but only in the structure's odd layers. These bits can be set with polarized light, and the even layers appear to protect the odd ones from the kind of field interference that bedevils other perovskites, according to the researchers.

Researchers from Cornell University managed to control the valley (orbital angular momentum) of electrons in a material by using electrical inputs to manipulate the magnetism of an adjacent material.

The device is built from a 2D tungsten diselenide (WSe₂), a material whose energy landscape has valleys, atop a few atomic layers of chromium triiodide ( CrI₃), a material whose magnetism can be electrically altered. The researchers are now looking for an alternative electrically-controlled magnetism material that will behave in a similar way at room temperatures.

They then changed the voltage across the CrI3 layers and measured the population of the WSe2 valleys using a technique that monitored the spin direction of light that the WSe2 emitted when illuminated by a laser. They found that the direction changed when the voltage was applied, indicating a switch in the semiconductor’s filled valley. The CrI3 layer is magnetic only at around 60 K, so the team says that their next step is to find a material that would allow valley sorting at room temperature.