Monday 10 March 2025
A team of researchers has made a significant discovery that sheds new light on the mysterious world of spin-orbit torques. These tiny forces, which are generated when an electric current flows through a material, have been found to be much more complex and nuanced than previously thought.
Spin-orbit torques are a type of torque that arises from the interaction between the spin of an electron and its orbital motion around the nucleus of an atom. This phenomenon was first discovered in the 1990s and has since been studied extensively in the field of materials science.
However, despite decades of research, many questions still remain unanswered about the nature of spin-orbit torques. For example, scientists have long wondered whether these forces can be harnessed to create new types of electronic devices that are faster, more efficient, and more powerful than those currently available.
To address this question, a team of researchers from several institutions in China conducted an extensive study of spin-orbit torques using advanced techniques such as spin torque ferromagnetic resonance. This technique involves applying a magnetic field to a material and measuring the resulting changes in its magnetization.
The results of their study revealed that spin-orbit torques are much more complex than previously thought, with multiple components that arise from different physical mechanisms. The researchers found that these forces can be divided into two main categories: damping-like torque and field-like torque.
Damping-like torque is a type of force that arises when the spin of an electron interacts with its orbital motion around the nucleus of an atom. This type of force is responsible for the slowing down of magnetic domains in materials, which is important for applications such as data storage devices.
Field-like torque, on the other hand, is a type of force that arises from the interaction between the spin of an electron and the magnetic field of the material. This type of force is responsible for the alignment of magnetic domains in materials, which is important for applications such as magnetoresistive random access memory (MRAM) devices.
The researchers also found that the strength of these forces can be controlled by adjusting the properties of the material, such as its composition and crystal structure. This means that it may be possible to design new types of electronic devices that are tailored to specific applications.
For example, a device that relies on damping-like torque could be designed to have a very high storage density, while a device that relies on field-like torque could be designed to have a very fast switching speed.
Cite this article: “Unraveling the Complexity of Spin-Orbit Torques”, The Science Archive, 2025.
Spin-Orbit Torques, Materials Science, Electron Spin, Orbital Motion, Torque Ferromagnetic Resonance, Magnetic Fields, Magnetization, Damping-Like Torque, Field-Like Torque, Nanotechnology
Reference: Qianbiao Liu, Lijun Zhu, “Absence of orbital current torque in Ta/ferromagnet bilayers” (2025).
