New Physics for Spintronics Say Researchers From Utah and UCI

As the world’s demand for faster and more efficient electronic devices continues to escalate, physicists are making strides in the field of spintronics, which leverages the unique properties of electron spin to encode, store, and transmit information. By harnessing both the charge and spin orientation of electrons, spintronic devices have the potential to revolutionize data storage and processing technologies.

A recent breakthrough in this field has been achieved by researchers at the University of Utah and the University of California, Irvine, who have discovered a new type of spin-orbit torque, dubbed the anomalous Hall torque, which enables the manipulation of spin and magnetization through electrical currents.

This phenomenon has far-reaching implications for the development of next-generation computing technologies, including neuromorphic computing, which mimics the human brain’s neural networks, and could pave the way for creating ultra-fast, energy-efficient devices that can perform complex tasks with unprecedented speed and accuracy.

Introduction to Spintronics and its Importance

Spintronics is an emerging field of research that aims to develop ultra-fast and energy-efficient electronic devices by utilizing both the charge and spin-orientation of electrons. Traditional electronics rely solely on the charge of electrons to encode, store, and transmit information, whereas spintronic devices leverage the additional property of electron spin to achieve improved performance. By assigning a value to electron spin (up=0 and down=1), spintronic devices offer a promising platform for meeting the increasing demand for electronic speed and capacity.

The development of viable spintronics requires a deep understanding of the quantum properties within materials, particularly the phenomenon of spin-torque. Spin-torque is crucial for the electrical manipulation of magnetization, which is essential for the next generation of storage and processing technologies. Researchers have been actively exploring various aspects of spintronics, including the discovery of new types of spin-orbit torques that can facilitate the manipulation of spin and magnetization through electrical currents.

Understanding Spin-Orbit Torque and its Variants

Spin-orbit torque refers to the speed at which electron spins rotate around a fixed point. In certain materials, electricity can sort electrons based on their spin orientation, leading to a distribution of spin-orientation known as symmetry. This symmetry influences the material’s properties, such as the directional flow of a ferromagnet’s magnetic field. The anomalous Hall torque is a recently discovered variant of spin-orbit torque that is related to the well-known anomalous Hall effect. This phenomenon describes how electrons are scattered asymmetrically when they pass through a magnetic material, resulting in a charge current that flows 90 degrees to the flow of an external electric current.

The anomalous Hall torque is characterized by the symmetry of how efficiently spin-orientation can be controlled in a material. Researchers have identified a triad of Hall-like spin-orbit torques, including the spin Hall torque and the planar Hall torque, which exhibit unique spin-torque symmetries. These Universal Hall torques are expected to be present in all conductive spintronic materials, providing a powerful tool for developing spintronics devices. The universality of these torques enables researchers to tune the properties of materials to achieve specific device functionalities.

Applications and Potential of Spintronics

The discovery of the anomalous Hall torque has significant implications for the development of spintronics devices. Researchers have demonstrated the first-ever spintronic prototype device that exploits the anomalous Hall torque effect, which can mimic the functionality of a neuron but is significantly smaller and operates at higher speeds. This device, known as a spin-torque oscillator, has the potential to perform neuromorphic tasks such as image recognition when interconnected into a larger network.

Traditional spintronics devices, such as Magnetoresistive Random Access Memory (MRAM), typically consist of a non-magnetic layer sandwiched between two ferromagnetic materials. However, the anomalous Hall torque enables the transfer of spin-orientation from a ferromagnetic conductor to an adjacent non-magnetic material, eliminating the need for a second ferromagnetic layer. This breakthrough has significant implications for the development of more efficient and compact spintronics devices.