Research / Technical

Materials scientists from the University of Groningen describe in two separate papers how complex oxides can be used to create very energy-efficient magneto-electric spin-orbit (MESO) devices and memristive devices with reduced dimensions.

The big challenges in next-gen microchips design are to design chips that are more energy efficient and to design devices that combine memory and logic (memristors). Tamalika Banerjee, Professor of Spintronics of Functional Materials at the Zernike Institute for Advanced Materials, University of Groningen, is looking at a range of quantum materials to create new devices. "Our approach is to study these materials and their interfaces, but always with an eye on applications, such as memory or the combination of memory and logic".

Scientists at the North Carolina State University, the University of North Carolina at Chapel Hill and Nanjing Normal University have made use of chiral phonons to transform wasted heat into spin information—without requiring magnetic materials.

This achievement could result in new classes of affordable and energy-efficient spintronic devices for use in applications from computational memory to power grids.

Researchers at MIT have proposed a new approach to making qubits and controlling them to read and write data. The method, which is theoretical at this stage, is based on measuring and controlling the spins of atomic nuclei, using beams of light from two lasers of slightly different colors. 

Nuclear spins have long been recognized as potential building blocks for quantum-based information processing and communications systems, and so have photons, the elementary particles that are discreet packets, or "quanta," of electromagnetic radiation. But coaxing these two quantum objects to work together was difficult because atomic nuclei and photons barely interact, and their natural frequencies differ by six to nine orders of magnitude. In the new process developed by the MIT team, the difference in the frequency of an incoming laser beam matches the transition frequencies of the nuclear spin, nudging the nuclear spin to flip a certain way.

An international research team led by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) has developed a new method for the efficient coupling of terahertz waves with much shorter wavelengths, so-called spin waves.

The team's experiments, in combination with theoretical models, clarify the fundamental mechanisms of this process previously thought impossible. The results are an important step for the development of novel, energy-saving spin-based technologies for data processing.

Researchers at Switzerland EPFL, China's Anhui University, Germany's University of Cologne and University of New Hampshire in the US have developed a technique that can visualize and control the rotation of a handful of spins arranged in a vortex-like texture at the fastest speed ever achieved. The breakthrough can advance spintronics devices like computer memory, logic gates, and high-precision sensors.

"The visualization and deterministic control of very few spins has not yet been achieved at the ultrafast timescales," says Dr. Phoebe Tengdin, a postdoc at EPFL, pointing out the very tight timeframes that this control needs to happen for spintronics to ever make the leap into applications. Now, the team developed a new technique that can visualize and control the rotation of a handful of spins arranged in a vortex-like texture, a kind of spin "nano-whirlpool" called a skyrmion.

Researchers from Osaka Metropolitan University and Osaka City University have succeeded in measuring spin transport in a thin film of specific molecules - a material well-known in organic light emitting diodes (OLEDs) - at room temperature. 

They found that this thin molecular film has a spin diffusion length of approximately 62nm, a length that could have practical applications in developing spintronics technology. In addition, while electricity has been used to control spin transport in the past, the thin molecular film used in this study is photoconductive, allowing spin transport control using visible light.

Researchers develop a super-hierarchical and explanatory analysis of magnetization reversal that could improve the reliability of spintronics devices. The researchers, led by Professor Masato Kotsugi from Japan's Tokyo University of Science, have developed an AI-based method for analyzing material functions in a more quantitative manner.

The team quantified the complexity of the magnetic domain structures using persistent homology, a mathematical tool used in computational topology that measures topological features of data persisting across multiple scales. The team further visualized the magnetization reversal process in two-dimensional space using principal component analysis, a data analysis procedure that summarizes large datasets by smaller “summary indices,” facilitating better visualization and analysis.

Researchers at Tohoku University, the University of Messina and the University of California, Santa Barbara (UCSB) have developed a scaled-up version of a probabilistic computer (p-computer) with stochastic spintronic devices that is suitable for hard computational problems like combinatorial optimization and machine learning.

The constructed heterogeneous p-computer consisting of stochastic magnetic tunnel junction (sMTJ) based probabilistic bit (p-bit) and field-programmable gate array (FPGA). ©Kerem Camsari, Giovanni Finocchio, and Shunsuke Fukami et al.

A p-computer harnesses naturally stochastic building blocks called probabilistic bits (p-bits). Unlike bits in traditional computers, p-bits oscillate between states. A p-computer can operate at room-temperature and acts as a domain-specific computer for a wide variety of applications in machine learning and artificial intelligence. Just like quantum computers try to solve inherently quantum problems in quantum chemistry, p-computers attempt to tackle probabilistic algorithms, widely used for complicated computational problems in combinatorial optimization and sampling.

Researchers from King Abdullah University of Science and Technology (KAUST) have shown that spintronics-based protective “logic locks” could be incorporated into the integrated circuits of electronic chips to defend chip security. This means that next-gen electronics could feature enhanced security systems built directly into their circuitry to help fend off malicious attacks. 

“The need for hardware-based security features reflects the globalized nature of modern electronics manufacture,” explains Yehia Massoud from KAUST. Electronics companies usually employ large specialized, external foundries to produce their chips, which minimizes costs but introduces potential vulnerabilities to the supply chain. The circuit design could simply be illegally copied by an untrusted foundry for counterfeit chip production or could be maliciously modified by the incorporation of “hardware Trojans” into the circuitry that detrimentally affects its behavior in some way.

Researchers at Beijing Institute of Technology and California Institute of Technology have developed a new theory and numerical calculations to predict spin decoherence in materials with high accuracy. This addresses the issue of spin coherence: quantum states can be easily disrupted, which is a problem when attempting to use them in a device; the electron spins need to preserve their quantum state for as long as possible to avoid loss of information. Spin coherence is so delicate that even the tiny vibrations of the atoms that make up the device can alter the spin state irreversibly.

Marco Bernardi, professor of applied physics, physics and materials science, explains: "Existing theories of spin relaxation and decoherence focus on simple models and qualitative understanding. After years of systematic efforts, my group has developed computational tools to study quantitatively how electrons interact and move in materials. This new paper has taken our work a few steps further: we have adapted a theory of electrical transport to study spin, and discovered that this method can capture two main mechanisms governing spin decoherence in materials—spin scattering off atomic vibrations, and spin precession modified by atomic vibrations. This unified treatment allows us to study the behavior of the electron spin in a wide range of materials and devices essential for future quantum technologies".