Andrew Corselli
Transistors, the building blocks of modern electronics, are typically made of silicon. Because it’s a semiconductor, this material can control the flow of electricity in a circuit. But silicon has fundamental physical limits that restrict how compact and energy-efficient a transistor can be.
MIT researchers have now replaced silicon with a magnetic semiconductor, creating a magnetic transistor that could enable smaller, faster, and more energy-efficient circuits. The material’s magnetism strongly influences its electronic behavior, leading to more efficient control of the flow of electricity.
The team used a novel magnetic material and an optimization process that reduces the material’s defects, which boosts the transistor’s performance.
The material’s unique magnetic properties also allow for transistors with built-in memory, which would simplify circuit design and unlock new applications for high-performance electronics.
"People have known about magnets for thousands of years, but there are very limited ways to incorporate magnetism into electronics. We have shown a new way to efficiently utilize magnetism that opens up a lot of possibilities for future applications and research," said Co-Lead Author Chung-Tao Chou, MIT Graduate Student.
Here is an exclusive Tech Briefs interview, edited for length and clarity, with Chou.
Tech Briefs: What was the biggest technical challenge you faced during the process of developing this magnetic transistor?
Chou: Basically, this material is relatively new; there has only been a gain of research interest in, I would say, the past five years or so. The challenging part was just to find the ideal material. The magnetic transistor only works with very specific magnetic structures; it doesn't work for any arbitrary magnets. It has to have these layered structures, and it also has to be a semiconductor. This material was only very recently discovered to meet all the criteria.
Tech Briefs: How did you overcome that?
Chou: We tried a few different materials and found that this material works the best. We also had to optimize how we make the device, because to make a transistor with these materials you have to have a very clean surface. We had to do some optimization for the device fabrication. After that we did some systematic characterization and found that this material works very well.
Tech Briefs: The article I read says, "The researchers plan to further study the use of electrical currents to control the device. They're also working to make their methods scalable so they can fabricate arrays of transistors." My question is: Do you have any set plans for further research or work?
Chou: We are quite confident about that. In general, electrical switching of magnets is pretty well-known in physics. Basically, in any magnetic memory you have to have a way to electrically control it. So, it's not a new thing. But, with this material, it's slightly different —we are expecting better performance than with traditional magnet switching.
The issue with random access memory made with traditional magnets is that you need to pass a lot of current to overwhelm the magnet in order to switch it. . But in our case, we don't need much current, so the switching should be very energy-efficient. That's the part that we are currently working on, and we are pretty confident about that.
We cannot share too much detail because it's still an ongoing process, and also it's not published yet.