Novel magnetic material with helix structure
- Mateo Cardinal
- 20 minutes ago
- 3 min read
A novel magnetic material with an extraordinary electronic structure might allow for the production of smaller and more efficient computer chips in the future: the p-wave magnet. Researchers from Karlsruhe Institute of Technology (KIT) were involved in its development. The magnetic behavior in the interior of this material results from the way the electron spins arrange themselves – in the shape of a helix. Therefore, the electric current flowing through is deflected laterally. The results are published in the “Nature” journal.
Magnetism, as we experience it every day, makes us usually think of materials such as iron, nickel, or cobalt that generate permanent magnetic fields or are attracted by magnetic forces. In these ferromagnetic materials, the spins, i.e. the moments of all electrons, move in the same direction. Antiferromagnetical materials, in contrast, seemingly do not have any magnetic effect because the magnetic forces and the electrical conductivity properties of the individual atoms neutralize each other – the spins of neighboring electrons point into opposite directions. However, recent developments revealed that, depending on the combination of their magnetic and electronic arrangements, antiferromagnets can take on ferromagnetic properties. Such a material has now been developed jointly by researchers of the RIKEN Center for Emergent Matter Science (CEMS) in Japan, the University of Tokyo, and KIT. In this material, the electrons behave as if their spins had been split, which has a significant effect on their movements. In this p-wave magnet, which is a combination of several different metals, the spins arrange themselves in a commensurate helix.
Magnetization Rotates by 360 Degrees
“The magnetization makes a full 360° rotation over a length of only six atomic lattice points with neighboring atoms being spaced apart from each other by almost exactly 60°,” says Dr. Jan Masell who heads the “MAGN3D” Emmy Noether Group at KIT’s Institute of Theoretical Solid-State Physics and visiting scientist at the CEMS. He was involved in the project coordinated by the University of Tokyo and the CEMS, which has been presented in the Nature journal now, reconciling the different theoretical approaches both with each other and with experimental measurements. “Additionally, our material exhibits a very low magnetization that is just about measurable, i.e. a little bit of ferromagnetism – this means that the helix is not perfect,” explains Masell.
This minimum deviation engenders a phenomenon that usually occurs in combination with a strong magnetic field or high magnetization: a giant anomalous Hall effect. Electrons that normally move in a straight line through a material are deflected laterally due to the inner structure of the p-wave magnet alone. “We were also able to demonstrate that the helix structure can be rotated within the magnetization – this means that the effect of the p-wave magnet can be switched,” adds Masell. “Moreover, the electrical resistance depends heavily on the orientation of the helix.”
Fundamental Research Offers New Opportunities
This fundamental research might open up new opportunities for information technology: For example, the metallic p-wave magnet might become the basis for faster, smaller, and more energy-efficient computer chips. At the same time, it provides a platform for the investigation of spin-electronic states, for example in magnets or superconductors.
Reference A metallic p-wave magnet with commensurate spin helix
Rinsuke Yamada, Max T. Birch, Priya R. Baral, Shun Okumura, Ryota Nakano, Shang Gao, Motohiko Ezawa, Takuya Nomoto, Jan Masell, Yuki Ishihara, Kamil K. Kolincio, Ilya Belopolski, Hajime Sagayama, Hironori Nakao, Kazuki Ohishi, Takashi Ohhara, Ryoji Kiyanagi, Taro Nakajima, Yoshinori Tokura, Taka-hisa Arima, Yukitoshi Motome, Moritz M. Hirschmann & Max Hirschberger
