Stanford University

This project seeks to advance early theoretical and experimental work on the quantum spin Hall system, a newly discovered type of material inside which the laws of electricity and magnetism are dramatically altered. Discovery of such new states of quantum matter could have profound implications on not only fundamental science but also computing technology. When electrons flow through metals or semiconductors, they dissipate energy as heat, causing devices to draw extra power and limiting computer processor speed. Such power dissipation is already the greatest roadblock to scaling semiconductor devices according to Moore’s Law. It is possible to move electrons without dissipation, but known methods have proved impractical, involving extremely low temperatures or large magnetic fields. Recently, a new type of dissipationless transport based on electron spin, rather than charge, has been discovered: the so-called quantum spin Hall (QSH) state in HgTe quantum wells. So far this phenomenon has been limited to cryogenic temperatures. The Stanford team proposes to experimentally test their theoretical prediction that a new class of materials could display the QSH effect at room temperature. Such a breakthrough would deepen understanding of this new state of matter and open the door to new dissipationless computing devices that would manipulate electrons by both charge and spin.