Take a rubber ball and throw it against a wall. It will bounce back to you every single time. This childhood pastime is also an exercise in classical physics, the laws of which are predictable and steady.
Now take that activity down to an infinitely small scale – the nano scale, where sizes are measured in one-billionths of meters and classical physics gives way to its strange cousin, quantum physics. Your “ball” is an electron, and when you toss it against a barrier or “wall” there’s always a very small chance that it will not bounce back but instead pass right through it.
Now you have a natural phenomenon that, if properly understood, can form the basis for tiny electrical switches controlling the next generation of super powerful quantum computers.
Putting a new ‘spin’ on switches
A physics researcher at Southern Illinois University Carbondale will spend the next five years developing and testing new magnetic materials that could be the basis for such “nanoswitches,” and he’ll be doing it with money from a prestigious grant aimed at establishing promising early-career researchers in their field.
Dipanjan Mazumdar, assistant professor in the physics degree program, just received a Faculty Early Career Development Program award – also known as a CAREER grant – from the National Science Foundation. The $500,000 grant will fund his work titled “Thermal Stability and Scaling of Nanoscale Spin-Electronic Devices Based on Novel Inverse-Heusler.”
Translated, the title means Mazumdar is looking for ways to exploit the different “spins” of electrons, an innate property they possess, along with a positive or negative charge, to make futuristic devices such as quantum computers a reality.
Magnetism drew him in
For Mazumdar, his interest in the topic started with a fascination with magnetism.
“When I started my research career, I learned that you can combine ultrathin nanoscale layers of magnetic materials to act as a switch, utilizing a subtle quantum physics effect called quantum tunneling.”
Quantum tunneling-based nanoswitches already are somewhat in use today in computers and hard drives. The read-head sensor that reads data from a magnetic hard drive, for example, is such a device, and many other familiar high-tech gadgets employ nanoscale electronic switches that rely exclusively on the charge property of the electron.
Along with its charge, however, electrons also possess the intrinsic property known as “spin,” which can be described as a spinning ball of charge. In spin-electronics, or “spintronics,” the spin property of the electron is exploited to make new devices, including quantum computers, Mazumdar said.
“We are still trying to make better, smaller, energy-efficient magnetic nanoswitches,” he said. “That is the goal of this project.”
‘Spin switch’ could revolutionize technology
A near-term technology goal for researchers such as Mazumdar is the creation of a so-called “spin switch.” Because of its construction, computers utilizing this kind of technology would not need to “boot up,” but instead would be turn on instantly. But many challenges remain before such an item with a long lifetime and high energy efficiency become a reality.
Mazumdar’s approach involves modifying the materials inside these tiny spintronic devices. Along with his collaborators, Mazumdar has designed several new magnetic materials for experimentation using thin-film growth at the nanoscale. Funded by the CAREER grant, the researchers will test the new materials in these nanoscale spin devices, looking at their switching and scaling ability, energy efficiency and speed.
Students also will benefit from the project, with Mazumdar working with several graduate, undergraduate, and high school students along the way. An outreach plan contained within the grant proposal also will promote interest in science and technology within the Southern Illinois area, he said.
Time to put theories to the test
The stakes are high, with success potentially leading to energy-efficient spin devices that could also show new ways to build the long-sought quantum computers of the future. But it will require teamwork, Mazumdar said.
“This is a very interdisciplinary area where physics, materials science and engineering come together,” he said. “To experimentally implement the design, we have to pay equal attention to all aspects, which are quite challenging.”
With much of the theoretical work already complete, most of the research now will take place in the laboratory, Mazumdar said, where theory faces the test of reality.
“All the chalkboard and computational work are by-and-large complete, at least to a point that we are ready to test them out experimentally,” Mazumdar said. “But very often physics says that certain materials will work in principle, but when we implement the material in the lab we encounter issues that the model did not take into account, or is detrimental to the property we are seeking.”
Despite the many challenges and unknowns, Mazumdar said the research and prospects for new discoveries are exciting.
“We need to keep trying, learning and getting wiser with each failure we encounter,” he said. “That is research, and I love it.”
