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Researchers at HZDR have partnered with the Norwegian University of Science and Technology in Trondheim, and the Institute of Nuclear Physics in the Polish Academy of Sciences to develop a method that facilitates the manufacture of particularly efficient magnetic nanomaterials in a relatively simple process based on inexpensive raw materials. Using a highly focused ion beam, they imprint magnetic nanostrips consisting of tiny, vertically aligned nanomagnets onto the materials. As the researchers have reported in the journal Advanced Functional Materials, this geometry makes the material highly sensitive to external magnetic fields and current pulses.
Nanomagnets play a key role in modern information technologies. They facilitate fast data storage, precise magnetic sensors, novel developments in spintronics, and, in the future, quantum computing. The foundations of all these applications are functional materials with particular magnetic structures that can be customized on the nanoscale and precisely controlled.
In the past, Dr. Rantej Bali and his colleagues at HZDR’s Institute of Ion Beam Physics and Materials Research had already developed processes for imprinting materials with tiny magnetic structures in varying geometries because the nature of the respective magnetic nanostructures determines how the material behaves in the application. Now the team has taken a crucial step forward: “We have managed to produce vertically aligned nanomagnets using a relatively simple material. This could make all technologies that are dependent on nanomagnets better and less expensive,” reports Bali.
In most materials, electron spins tend to lie horizontally along the surface and not point outward. This severely restricts applications. Now the researchers have been able to demonstrate that by drastically reducing the size of the magnetic fields the spins can be forced to stand out vertically from the material’s surface. Although conventional methods achieve similar behavior, they need raw materials with complex crystal structures or combine different materials in thin layers, making this method complicated and expensive. This new development is quite different: “Both the materials and the manufacture are inexpensive and suitable for most magnetic application scenarios,” explains Bali.
The secret is in the reduction: ion beam magnetic engraving
The researchers used a thin metallic film of iron-vanadium alloy as their raw material. In their disordered form, the atoms of this material initially exhibit only weak magnetism. But this all changes when they are bombarded with a highly focused ion beam. The principle behind this is that when a beam with a diameter of just two nanometers hits the material, it reorganizes the atoms locally into a crystal lattice. The ions effectively push the atoms into place in the lattice. In the ordered, crystalline state, the material becomes ferromagnetic. Thus, bit by bit, miniscule magnetic fields are created in the film. While the precise physical mechanism is as yet unknown, it is clear that this process allows magnetic nanostructures to be produced in almost any geometry and size.
Unlike in earlier attempts, this time, the researchers reduced the width of the nanostrips until they finally obtained extremely thin magnetic fields just 25 nanometers wide. Contrary to their expectation, they discovered that the nanometer-sized areas in the very thin strips suddenly stood out vertically from the surface.
Vertical nanomagnets are more efficient
Vertically aligned nanomagnets are advantageous for a number of reasons: first, they can be accommodated much more compactly. This increases the data storage density of hard disks, for example, and supports the trend towards ever more miniaturized components. Second, they make the materials more efficient, for instance in spintronics which uses not only the electrons’ charge but also their spin for signal transport. When electric current flows through the material, vertical moments exert a greater torque on the electrons than parallel moments. Quantum computers can also benefit from vertically aligned nanomagnets to distinguish between the two possible ground states of a qubit, which correspond to an upward or downward magnetic alignment, and to control them with high sensitivity.
“To put it very simply, it’s rather like a game of cards. If you put down all the cards next to each other on the table, they need quite a lot of space. Instead, if you stand them up, it saves a lot of space. One card, standing up, responds much more sensitively to stimuli than one lying down. The same is true of the nanomagnets’ response to external magnetic stimuli,” illustrates Bali.
Experimental and theoretical proof
In order to understand the results of their experiments even better, the researchers conducted further tests to observe how magnetic domains form in material. These are areas in which all magnetic moments are aligned in the same direction. When two opposite domains collide, the magnetization must change direction within the domain wall, the narrow boundary area only a few nanometers wide. The result is that the magnetic moments align themselves vertically.
The team at HZDR was initially able to demonstrate this special twist using magnetic force microscopy and scattered fields. The NTNU team, working with Magnus Nord, then measured the finished material again using the so-called differential phase contrast method, which produces nanoscale images showing how electrons deflect when passing through magnetic areas. This allowed the researchers to map the magnetization of the stripes in two dimensions and visualize the boundaries between different magnetic domains. Michal Krupinski’s team in the Institute of Nuclear Physics at the Polish Academy of Sciences in Kraków added theoretical simulations and provided the visualization that shows how precisely the domain boundaries force the magnetic moments into the vertical position. The teams now want to build on their joint new findings to continue developing future technologies for magnetic storage, sensors, and spin-based quantum computing.
Publication:
M. S. Anwar, I. Zelenina, P. Sobieszczyk, G. Hlawacek, K. Tveitstøl, K. Potzger, J. Fassbender, O. Hellwig, J. Lindner, M. Krupiński, M. Nord, R. Bali, Confinement Driven Spin-Texture Evolution in Directly Written Nanomagnets, in Advanced Functional Materials, 2025, (DOI: 10.1002/adfm.202513904)
Additional information:
Dr. Rantej Bali
Institute of Ion Beam Physics and Materials Research at HZDR
Phone: +49 351 260 2461 | Email: r.bali@hzdr.de
Media contact:
Simon Schmitt | Head
Communications and Media Relations at HZDR
Phone: +49 351 260 3400 | Mob.: +49 175 874 2865 | Email: s.schmitt@hzdr.de
The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) performs – as an independent German research center – research in the fields of energy, health, and matter. We focus on answering the following questions:
• How can energy and resources be utilized in an efficient, safe, and sustainable way?
• How can malignant tumors be more precisely visualized, characterized, and more effectively treated?
• How do matter and materials behave under the influence of strong fields and in smallest dimensions?
To help answer these research questions, HZDR operates large-scale facilities, which are also used by visiting researchers: the Ion Beam Center, the Dresden High Magnetic Field Laboratory and the ELBE Center for High-Power Radiation Sources.
HZDR is a member of the Helmholtz Association and has six sites (Dresden, Freiberg, Görlitz, Grenoble, Leipzig, Schenefeld near Hamburg) with almost 1,500 members of staff, of whom about 700 are scientists, including 200 Ph.D. candidates.
Dr. Rantej Bali
Institute of Ion Beam Physics and Materials Research at HZDR
Phone: +49 351 260 2461 | Email: r.bali@hzdr.de
M. S. Anwar, I. Zelenina, P. Sobieszczyk, G. Hlawacek, K. Tveitstøl, K. Potzger, J. Fassbender, O. Hellwig, J. Lindner, M. Krupiński, M. Nord, R. Bali, Confinement Driven Spin-Texture Evolution in Directly Written Nanomagnets, in Advanced Functional Materials, 2025, (DOI: 10.1002/adfm.202513904)
https://www.hzdr.de/presse/magnetic_nanomaterials
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A nano-focused neon ion beam creates a spatially limited lattice order in an alloy. This results in ...
Quelle: Sander Münster
Copyright: Sander Münster/HZDR
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