From Johannes Gutenberg University Mainz (JGU), Germany

How much energy is consumed each time we upload an image to social media, which relies on data centers and cloud storage? Data centers currently account for about 1% of global energy consumption, amounting to 200 terawatt-hours of electricity annually. This immense energy demand has driven researchers to explore innovative ways to reduce energy usage.

New approach is equally suitable for smartphones and supercomputers
A team of scientists at Johannes Gutenberg University Mainz (JGU) in Germany has now achieved a groundbreaking advancement in memory technology in close collaboration with Antaios, a magnetic random access memory company in France. Their innovation, based on Spin-Orbit Torque (SOT) Magnetic Random-Access Memory (MRAM), offers a highly efficient and powerful solution for data processing and storage – a transformative step forward for technologies ranging from smartphones to supercomputers.

“This prototype is one of a kind and could revolutionize data storage and processing. It aligns with global goals to reduce energy consumption and paves the way for faster, more efficient memory solutions,” said Dr. Rahul Gupta, former postdoctoral researcher, JGU Institute of Physics, where he supervised the research, and the lead author of the study recently published in Nature Communications.

SOT-MRAM stands out for its superior power efficiency, nonvolatility, and performance compared to static RAM, making it a strong candidate to replace cache memory in computer architecture, for example. This cutting-edge technology uses electrical currents to switch magnetic states, enabling reliable data storage. However, one key challenge has been to reduce the high input current required during the writing process while ensuring industrial compatibility. This includes maintaining sufficient thermal stability to store the data for over ten years and minimizing the energy required to perform the storage task.

By exploiting previously neglected orbital currents, researchers at JGU and Antaios have developed a unique magnetic material incorporating elements such as Ruthenium as a SOT channel a fundamental building block of SOT MRAM – to significantly enhance performance.

Their innovation includes:

• Over 50% reduction in overall energy consumption compared to existing memory technologies on an industrial scale;
• 30% boost in efficiency, enabling faster and more reliable data storage;
• 20% reduction in the input current required for magnetic switching to store the data;
• Achievement of a thermal stability factor that ensures data storage longevity of more than 10 years.

Secret behind efficient memory
The breakthrough leverages a phenomenon known as the Orbital Hall Effect (OHE), enabling greater energy efficiency without relying on rare or expensive materials. Traditionally, SOT-MRAM relied on the spin property of electrons, where charge current is converted into spin current via the Spin Hall Effect. This process requires elements with high spin-orbit coupling, typically rare and expensive, often environmentally unfriendly, high atomic number materials such as platinum and tungsten. “In contrast, our approach harnesses a novel fundamental phenomenon by utilizing orbital currents derived from charge currents through the Orbital Hall Effect, eliminating the dependency on costly and rare materials,” explained Dr. Rahul Gupta.

Dr. Gupta further explained that by combining this innovative approach with state-of-the-art engineering, the team has developed a scalable and practical solution ready for integration into everyday technology. This research exemplifies how scientific advancements can address some of the most pressing challenges of our time. With global energy consumption steadily increasing, breakthroughs like this highlight the crucial role of technology in creating a more sustainable future.

Successful industrial collaboration
JGU project coordinator Professor Mathias Kläui emphasized his excitement about the successful collaboration with the team of Dr. Marc Drouard, Antaios, France: “I am delighted that this collaborative effort has resulted in this exciting device concept, which is not only fascinating from a basic science point of view but might have implications in industry for GreenIT.” He continued: “Reducing power consumption by discovering innovative physical mechanisms that allow for the development of more efficient technologies is one of the aims of our research.“

The study was recently published in Nature Communications (see below) and has been supported by the industrial partner Antaios, the EU Research and Innovation program Horizon 2020 and Horizon Europe, the European Research Council, the German Research Foundation (DFG), and the Norwegian Research Council.

Article: Harnessing orbital Hall effect in spin-orbit torque MRAM

Nature Communications has published an article written by Rahul Gupta, Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany, Chloé Bouard, Antaios, 38240, Meylan, France, Fabian Kammerbauer, J. Omar Ledesma-Martin, Arnab Bose, Iryna Kononenko, Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany, Sylvain Martin, Perrine Usé, Antaios, 38240, Meylan, France, Gerhard Jakob, Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany, and Graduate School of Excellence Materials Science in Mainz, 55128, Mainz, Germany, Marc Drouard, Antaios, 38240, Meylan, France, Mathias Kläui, Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany, Graduate School of Excellence Materials Science in Mainz, 55128, Mainz, Germany, and Department of Physics, Center for Quantum Spintronics, Norwegian University of Science and Technology, 7491, Trondheim, Norway.

Abstract: “Spin-Orbit Torque (SOT) Magnetic Random-Access Memory (MRAM) devices offer improved power efficiency, nonvolatility, and performance compared to static RAM, making them ideal, for instance, for cache memory applications. Efficient magnetization switching, long data retention, and high-density integration in SOT MRAM require ferromagnets (FM) with perpendicular magnetic anisotropy (PMA) combined with large torques enhanced by Orbital Hall Effect (OHE). We have engineered a PMA [Co/Ni]₃ FM on selected OHE layers (Ru, Nb, Cr) and investigated the potential of theoretically predicted larger orbital Hall conductivity (OHC) to quantify the torque and switching current in OHE/[Co/Ni]₃ stacks. Our results demonstrate a  ~30% enhancement in damping-like torque efficiency with a positive sign for the Ru OHE layer compared to a pure Pt layer, accompanied by a  ~20% reduction in switching current for Ru compared to pure Pt across more than 250 devices, leading to more than a 60% reduction in switching power. These findings validate the application of Ru in devices relevant to industrial contexts, supporting theoretical predictions regarding its superior OHC. This investigation highlights the potential of enhanced orbital torques to improve the performance of orbital-assisted SOT-MRAM, paving the way for next-generation memory technology.“