Toward “valleytronic” devices for data storage or computer logic systems

    Researchers have discovered a new way to tune electronic energy levels in some 2-D materials.

    MIT Valleytronics 1 Laser Web
    Researchers at MIT have discovered a new way of using laser light to tune electronic energy levels in two-dimensional films of crystal. The discovery could ultimately pave the way for the development of so-called “valleytronic” devices, which harness the way electrons gather around two equal energy states, known as valleys. Photo, Jose-Luis Olivares, MIT.

    Faster, more efficient data storage and computer logic systems could be on the horizon thanks to a new way of tuning electronic energy levels in two-dimensional films of crystal, discovered by researchers at MIT.

    The discovery could ultimately pave the way for the development of so-called “valleytronic” devices, which harness the way electrons gather around two equal energy states, known as valleys.

    Engineers have for some time warned that we are reaching the limits of how small we can build conventional electronic transistors, which are based on electrons’ electrical charge.

    As a result, researchers have been investigating the utility of a property of electrons known as spin, to store and manipulate data; such technologies are known as spintronics.

    But as well as their charge and spin, electrons in materials also have another “degree of freedom,” known as the valley index. This is so-called because plotting the energy of electrons relative to their momentum results in a graph consisting of a curve with two valleys, which are populated by electrons as they move through a material.

    Harnessing this degree of freedom could allow information to be stored and processed in some materials by selectively populating the two valleys with electrons.

    However, developing such valleytronic devices requires a system to selectively control the electrons within the two valleys, which has so far proven very difficult to achieve.

    In a paper published March 9 in the journal Science, researchers led by Nuh Gedik, an associate professor of physics at MIT, describe a new way of using laser light to control the electrons in both valleys independently, within atomically thin crystals of tungsten disulfide.

    Read more at the MIT News Office.

    Helen Knight | MIT News correspondent
    March 9, 2017