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An interview with this year’s recipient of APS’s biggest research award.
By Kendra Redmond | December 12, 2023
Credit: MPI für Mikrostrukturphysik / Marco Warmuth
Parkin at the Max Planck Institute of Microstructure Physics in October 2023.
Stuart Parkin grew up surrounded by books. “My father read thousands,” he recalls from his early years in Watford, England. Now an experimental physicist and director at the Max Planck Institute of Microstructure Physics in Halle, Germany, Parkin has his own collection of books.
But unlike his father, Parkin can access his titles anytime, from anywhere in the world. "I have hundreds of books on my phone,” he says. “It's amazing." That sweeping digital shift is due, in part, to Parkin's own research.
While at IBM Research in the late 1980s, Parkin invented a highly sensitive magnetic field detector. Thanks to his spin valve, the storage capacity of magnetic disk drives soared by a factor of 1,000, then 10,000. Most digital data is still stored on magnetic disk drives utilizing his technology.
IBM sold its disk drive business in 2002. "Ten thousand people were working on the business, and it just disappeared overnight," Parkin says. He took it as a challenge: "What could we do that would be better than a disk drive?" He’s now 20 years into making that next technology, racetrack memory, a reality.
Parkin’s innovative research has earned him dozens of high-profile awards and accolades over the years — including, now, the 2024 APS Medal for Exceptional Achievement in Research, APS’s largest prize. The award recognizes Parkin “for major discoveries in spintronics leading to a revolution in data storage and memory.”
Parkin spoke with APS News about his passion for fundamental science that makes the world better, his innovative work on memory storage, and why he tells his students to “go beyond.”
This interview has been edited for length and clarity.
What sparked your interest in physics?
Both my parents went to university, and they were very interested in books and reading. That environment encouraged me to learn about other cultures and the world itself. I read a lot of books when I was a kid.
I was going to do chemistry at Cambridge, but my tutor told me, "You should really do something much more fundamental — physics or mathematics — because they can explain the world." I liked that concept. It’s extraordinary that you can explain so much of the world from just a small number of equations.
What have been the central themes of your research?
My main interests have been how to build new materials one atomic layer at a time, and the interfaces between materials. An interface between material A and material B can give rise to properties that you don't find in the individual materials themselves. It is very difficult to calculate what that interface structure might be; it's more intuitive. That's the way I like to do science.
I'm very interested in exploring how we can use fundamental science discoveries to build new technologies — not tomorrow, but maybe in 10, 20, or 30 years. I’m very patient; it takes a very long time to understand even a tiny part of the natural world. I'm most excited when I can imagine ways of using some scientific concept or new material to help solve one of the challenges of today and make society better for all of us.
What is racetrack memory?
Racetrack has two important distinctions from conventional memory. In conventional memory, a device typically has a single bit, and the data is stored in a fixed location. In racetrack, the data is stored in magnetic spin texture walls, or boundaries between two magnetic regions. The idea is that in a very, very thin and narrow magnetic nanowire, we can store a whole sequence of these magnetic domain walls.
By passing current in this magnetic wire, you can move the data physically along the wire without moving any atoms — just by rotating magnetic spins. This means that in one device, we could perhaps store 100 bits of information. Moreover, the information can be physically moved along that wire to devices to read and write. It's conceptually very different from any memory today.
I proposed the concept in 2002, and we've effectively demonstrated that it's even better than I thought. New physics we've discovered has enabled us to manipulate these domain walls with current pulses 20 to 50 times faster than was theoretically possible 20 years ago.
Our vision is that in the next 10 years, we'll have demonstrated that we can build horizontal racetracks. If we stack several horizontal racetracks, one on top of the other, we could build very interesting devices with high performance, low energy, high volumetric capacity, and low breakdown, so they could have a million times better performance than a magnetic disk drive.
Are you working on other projects as well?
I have many! For example, if you take a conventional superconductor and inject that supercurrent into certain types of materials, including magnetic materials, you can create different forms of superconducting currents — in particular, triplet pairing. This is very interesting if the triplet Cooper pairs carry angular momentum. Our goal is to use that angular momentum at very low temperatures to manipulate magnetization and maybe build a cryogenic racetrack using totally different physics than the physics we're using today.
I'm also very interested in neuromorphic computing. The brain is very energy efficient; it uses 20 watts. To get the equivalent computing power today using CMOS, you need 10 megawatts. There are potentially huge possibilities to create ultralow energy computing systems by better understanding how the brain is able to compute.
How do you balance your research projects, director responsibilities, and other professional activities?
I'm very motivated by science. I'm super excited by what I do, and working with all the young people here is fantastic. Being a scientist is really the best job in the world. I’m always meeting new people and getting new ideas. But there are so many things to do and so many demands on my time. A lot of people are very unhappy that I don't respond to their emails quickly enough (laughs). It’s impossible to keep track of all these emails.
Aside from patience and not worrying too much about email, what makes you good at what you do?
This is terrible to say, but I don’t read a lot of papers. If you read too many papers in the scientific literature, you can start to think like everybody else. I don't want to discourage people from reading the literature, but sometimes you can have more new ideas if you don't.
I’m also very persistent. If I have an idea and want to prove it, I'll continue working on it even if the experiments show something else. Eventually, I’ll have the right intuition. Of course, I'll change my mind if I discover my idea is wrong, but many people give up when they just have to persevere.
What advice do you share with your students?
I tell my students to “go beyond,” which means that we should go beyond what others are doing — that we should come up with our own ideas. I also like to say, “You should do the impossible.” Come up with something that nobody has done, and then imagine ways of achieving that goal if it's exciting from a fundamental science point of view or if you can imagine it being technologically useful. And then never give up. It's very exciting to try to achieve something that nobody has done before.
Kendra Redmond is a writer based in Minnesota.
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