The foundations of modern electronics, from the smartphones in our pockets to the supercomputers that power scientific research, are built on silicon. This ubiquitous semiconductor material has been the backbone of technological progress for decades, but its era of dominance is facing fundamental physical limits that threaten to slow down innovation. In light of this challenge, a team of researchers from the prestigious Massachusetts Institute of Technology (MIT) has presented a revolutionary solution: a magnetic transistor that not only overcomes the limitations of silicon but also opens the door to a completely new generation of smaller, faster, and drastically more energy-efficient electronic devices.

A standstill at the end of Moore's Law

Transistors, the miniature switches that control the flow of electric current, are the basic building blocks of every digital circuit. Their evolution has been driven by Moore's Law, a prophetic observation that the number of transistors on an integrated circuit doubles approximately every two years. However, as transistor dimensions shrink to the nanometer scale, engineers are encountering insurmountable obstacles. Silicon, as a semiconductor, has an inherent limit on the minimum voltage required for operation, which directly affects energy consumption. Further miniaturization leads to problems such as current leakage and excessive heating, which limit performance and reliability. In essence, the era of exponential growth enabled by silicon is approaching its physical end, forcing the scientific community to search for radically new approaches.

Spintronics: A new paradigm for controlling electronics

The answer to the silicon crisis may lie in spintronics, a relatively young but extremely promising branch of physics. While traditional electronics are based on controlling the charge of an electron, spintronics exploits another of its fundamental quantum properties – spin. Spin can be simply imagined as the tiny internal magnetism of an electron, which gives it an "up" or "down" orientation. These two states can be used to encode binary information (0 and 1), just as the flow or absence of current does in classic transistors. The key advantage lies in the fact that it takes considerably less energy to change the spin than to move the electron current. It was this idea that guided the MIT team in developing the magnetic transistor, a device that uses magnetism for ultra-efficient control of an electrical signal.

Chromium sulfide bromide: The material that changes everything

At the heart of this technological breakthrough is an exotic material called chromium sulfide bromide ($CrSBr$). It is a two-dimensional material, meaning it can exist in layers just one atom thick. But, unlike other well-known 2D materials like graphene, $CrSBr$ possesses a unique combination of properties: it is simultaneously a semiconductor and a magnet. Chung-Tao Chou, one of the lead authors of the study published on September 25, 2025, in the prestigious journal Physical Review Letters, pointed out that the search for the right material was one of the biggest challenges. "We tried many other materials that simply didn't work," he explained. $CrSBr$ proved to be ideal because its magnetic states can be switched from one to the other very cleanly and smoothly, which is crucial for the reliable operation of a transistor as a switch. An additional, by no means negligible, advantage is its stability in air, which greatly simplifies the manufacturing process compared to other sensitive 2D materials.

Revolutionary performance and elegant fabrication

The way the researchers constructed the device is as innovative as the material itself. On a silicon substrate with pre-placed electrodes, they carefully transferred an extremely thin layer of chromium sulfide bromide, only a few tens of nanometers thick. In doing so, they used a simple but ingenious transfer method using adhesive tape. This approach, according to Chou, eliminates the need for solvents or adhesives that can contaminate the sensitive surface of the material and degrade the transistor's performance. The cleanliness of the interface between the material and the electrodes proved to be key to achieving outstanding results.

The performance of the new magnetic transistor far surpasses all previous attempts. While previous magnetic devices could change the current flow by only a few percent, MIT's transistor achieves a change by a factor of as much as 10. This means it can amplify or cut off an electrical signal with unprecedented efficiency. The scientists showed that the magnetic state of the material, and thus the state of the transistor ("on" or "off"), can be controlled using an external magnetic field with minimal energy consumption. Even more importantly for practical application, they proved that the same control can be achieved by applying an electric current, which is a prerequisite for integrating millions of such transistors onto a single chip.

A transistor with built-in memory: The end of the computing bottleneck

Perhaps the most exciting aspect of this discovery is the fact that the unique magnetic properties of $CrSBr$ allow transistors to have built-in memory. In today's computers, processing (performed by the processor) and data storage (in RAM) are physically separate. Constantly transferring data between these two components creates the so-called "von Neumann bottleneck," which consumes precious time and energy and is one of the main limitations of modern computer architectures.

The magnetic transistor from MIT elegantly solves this problem by merging both functions into a single device. It not only processes information (as a switch) but also remembers it at the same time (retaining its magnetic state even when the power is off). "Now the transistors not only turn on and off, they also remember information," explains Luqiao Liu, an associate professor at MIT and one of the senior authors of the paper. "And because we can switch the transistor state with a much greater magnitude, the signal is significantly stronger, allowing us to read the stored information faster and more reliably." This concept, known as "in-memory computing," could lead to radically simpler and more powerful circuit designs and pave the way for the development of neuromorphic chips that mimic the efficiency of the human brain.

A glimpse into the future of electronics

Although the demonstration of this magnetic transistor is a huge scientific success, the path to commercial application still requires further research. The team now plans to study in more detail the methods of controlling the device using electric current and to work on the scalability of the process so they can produce not only individual transistors but entire arrays, which is the basis for creating complex integrated circuits. Although there are challenges, such as ensuring optimal operation at room temperatures and perfecting mass production, this work represents a key step towards the post-silicon era. It opens the horizon for the development of electronics that are not only more powerful but also fundamentally more efficient, which could have far-reaching consequences for everything from battery life in mobile devices to energy consumption in the massive data centers that power artificial intelligence and cloud services.