Ordinary computers keep memory and calculation apart and spend energy moving data between them. The brain does both jobs in the same junctions, called synapses. Neuromorphic hardware tries to copy that idea. Researchers in a collaboration that includes the University of Edinburgh created a magnetic version of a synapse, built from skyrmions. Skyrmions are tiny whirlpool-like patterns in a magnet - stable knots in the local magnetic moments, the little arrows that describe how atoms in a magnet point. Skyrmions can be very small and keep their state without constant power, so they have long been discussed as bits for memory. Earlier devices often created or destroyed skyrmions one by one. Those events can be random, which makes a reliable synapse hard to build.
A signal that can be tuned at room temperature
The researchers used a thin magnetic crystal called Fe₃GaTe₂. It is a van der Waals ferromagnet, meaning its layers stick together by weak forces and it stays magnetic on its own. In this crystal, a whole lattice of skyrmions can change together into striped magnetic domains. The change is collective and repeatable
A whole lattice of skyrmions can change together into striped magnetic domains. That collective shift produces a steady change in the anomalous Hall resistance, a sideways electrical voltage that appears when current flows through a magnet. The voltage stands for the synaptic weight, the number that says how strong the junction is. Electrical pulses of different length set several weights. A future smaller device might use about 0.66 picojoules per operation, a trillionth of a joule, similar to other memory-like electronic parts. When the measured curves were placed in a simulated network, handwritten digits were recognized with about 96.1 percent accuracy. The effect works at room temperature.
This could lead to spin-based hardware, in which information is stored in the orientation of magnetic moments.The researchers have described the methods and results of this study in a paper published in Advanced Materials.