Regular electronics use an electron's charge to encode information; spintronic devices use the spin of an electron to achieve the same thing.
Using this intrinsic property of an electron has the potential to make high-powered devices that use much less power. However, the area of research is very new, and there are some fundamental base knowledge challenges that need to be resolved.
New research develops precise testing ground
We are one step closer to those answers thanks to the development of a new testing ground of quantum systems that can turn particle interactions on and off.
This new testing ground will assist researchers to improve their control of spin information. It will help to answer one of the most pressing questions from the field that relates to how the signal carried by particles with spin, known as spin current, decays over time.
“The signal we need to make spintronics work, and to study these things, can decay. Just like we want good cell phone service to make a call, we want this signal to be strong,” said Chuan-Hsun Li, a graduate student in electrical and computer engineering at Purdue University.
“When spin current decays, we lose the signal.”
Spin decay knowledge fundamental
Electrons interact with everything around them and display different properties within themselves. The interaction between a particle's spin and momentum is known as spin-orbit coupling.
The new research shows that spin-orbit coupling and interactions with other particles can dramatically enhance spin decay in a quantum fluid called Bose-Einstein condensate (BEC).
“People want to manipulate spin formation so we can use it to encode information, and one way to do this is to use physical mechanisms like spin-orbit coupling,” Li said.
“However, this can lead to some drawbacks, such as the loss of spin information.” The recent research was completed by Professor of physics and astronomy, and electrical and computer engineering at the University of Purdue, Yong Chen.
Chen and his team created a device that can be described as a mini particle collider for BECs. The device uses lasers to cool Rubidium-87 atoms within a vacuum chamber to absolute zero. Under these conditions, the atoms become a BEC. This is the coldest and strangest of the five states of matter.
At this quantum state atoms begin to exhibit wave-like properties, as they get colder they begin to overlap and stop acting as individuals. While not technically a gas, it is easier to imagine the BEC state as a gas.
Physicists colloquially refer to the state as quantum fluid or quantum gas. Inside the mini-collider, Chen sent two BECs with opposite spins smashing into one another. Just like two different gases would, when they hit, they partially penetrated each other and delivering a spin current.
Controlled testing ground open doors to more research
“A lot of fascinating phenomena occur when you collide two condensates. Originally, they’re superfluid, but when they collide, part of the friction can turn them to thermal gas,” Chen said.
“Because we can control every parameter, this is a really efficient system to study these kinds of collisions.”
Using this setup the scientist can turn spin-orbit coupling on and off which allows them to exactly study its effects on spin current decay.
Chen hopes that they can continue to use their experimental testing ground and their bosonic spin current to continue to understand better the fundamentals of spin transport and quantum dynamics which will lead to more advanced spintronic devices.