Working with a manganese oxide-based quantum material known as NSMO - which is used in devices where information is stored by using a magnetic field to switch from one electron spin state to another (a method known as spintronics) - the researchers found that a pulse of laser light can dramatically change the spin state of the material while leaving its orbital state intact. Until now, the electron spins and orbitals - the regions within an atom that the electron will most likely occupy - of the material were thought to go hand in hand, i.e., were "correlated," and not able to be changed independently.
The research results, say the scientists, opens a path toward a new generation of logic and memory devices that could be 10,000 times faster than today's.
"What we're seeing in this system is the complete opposite of what people have seen in the past," says Lingjia Shen, a SLAC research associate and one of the lead researchers for the study. "It raises the possibility that we could control a material's spin and orbital states separately, and use variations in the shapes of orbitals as the 0s and 1s needed to make computations and store information in computer memories."
A common way to investigate this type of material is to hit it with laser light to see how its electronic states respond to an injection of energy. To do so, the researchers observed the material's response with X-ray laser pulses from SLAC's Linac Coherent Light Source (LCLS).
According to the researchers, they expected to see that orderly patterns of electron spins and orbitals in the material would be thrown into total disarray, or "melted," as they absorbed pulses of near-infrared laser light. Instead they observed that only the spin patterns melted, while the orbital patterns stayed intact - completely breaking the normal coupling between the spin and orbital states. This, say the researchers, is a challenging