Shearing of atomic layers in layered iron phosphorus trisulfide is triggered by scrambling of electron spin upon exposure to light pulse. Purchased spins on left; scrambled spins on.
Advanced ultrafast imaging techniques have exposed ultrafast mechanical movement tied to a modification in magnetic state in a layered product. This intriguing magnetic impact might have applications in nanodevices requiring quick and ultra-precise movement control.
A common metal paper clip will stay with a magnet. Researchers classify such iron-containing products as ferromagnets. A little over a century earlier, physicists Albert Einstein and Wander de Haas reported a surprising effect with a ferromagnet. They discovered that when you suspend an iron cylinder from a wire and expose it to a magnetic field, it starts turning if the direction of the magnetic field is reversed.
” Einstein and de Haass experiment is nearly like a magic show,” stated Haidan Wen, a physicist in the Materials Science and X-ray Science departments of the U.S. Department of Energys (DOE) Argonne National Laboratory.” You can trigger a cylinder to rotate without ever touching it.”
” In this experiment, a microscopic home, electron spin, is made use of to elicit a mechanical response in a cylinder, a macroscopic object.”
— Alfred Zong, Miller Research Fellow at the University of California, Berkeley
In the scientific journal Nature, a group of researchers from Argonne and other U.S. national labs and universities now report an analogous yet various impact in an” anti”- ferromagnet. This might have essential applications in devices needing ultra-precise and ultrafast movement control. One example is high-speed nanomotors for biomedical applications, such as use in nanorobots for minimally invasive diagnosis and surgery.
Electron Spin and Its Role
The difference between a ferromagnet and antiferromagnet has to do with a property called electron spin. This spin has an instructions. Reversing the magnetic field reverses the instructions of the electron spins.
” In this experiment, a microscopic home, electron spin, is made use of to generate a mechanical action in a cylinder, a macroscopic item,” stated Alfred Zong, a Miller Research Fellow at the University of California, Berkeley.
Antiferromagnet Experiment
In antiferromagnets, rather of the electron spins all pointing up, for instance, they alternate from approximately down between surrounding electrons. These opposite spins cancel each other out, and antiferromagnets hence do not react to changes in an electromagnetic field as ferromagnets do.
” The concern we asked ourselves is, can electron spin elicit an action in an antiferromagnet that is different however comparable in spirit to that from the cylinder rotation in the Einstein-de Hass experiment?” Wen stated.
To respond to that concern, the group prepared a sample of iron phosphorus trisulfide (FePS3), an antiferromagnet. The sample included multiple layers of FePS3, with each layer being only a couple of atoms thick.
” Unlike a traditional magnet, FePS3 is special due to the fact that it is formed in a layered structure, in which the interaction between the layers is extremely weak,” stated Xiaodong Xu, professor of physics and materials science at the University of Washington.
Outcome of Experiment
” We developed a set of corroborative experiments in which we shot ultrafast laser pulses at this layered material and determined the resultant changes in material residential or commercial properties with optical, X-ray, and electron pulses,” Wen added.
The group found that the pulses change the magnetic property of the product by rushing the ordered orientation of electron spins. The arrows for electron spin no longer alternate in between up and down in an organized fashion, but are disordered.
” This scrambling in electron spin results in a mechanical action across the entire sample. Due to the fact that the interaction between layers is weak, one layer of the sample is able to slide back and forth with regard to an adjacent layer,” discussed Nuh Gedik, teacher of physics at the Massachusetts Institute of Technology (MIT).
This movement is ultrafast, at an unbelievable 10 to 100 picoseconds per oscillation. One picosecond equates to just one trillionth of a second. This is so quick that in one picosecond, light travels a mere third of a millimeter.
Measurements on samples with spatial resolution on the atomic scale and temporal resolution measured in picoseconds need first-rate scientific facilities. To that end, the group depended on cutting-edge ultrafast probes that use electron and X-ray beams for analyses of atomic structures.
Encouraged by optical measurements at the University of Washington, the initial research studies utilized the mega-electronvolt ultrafast electron diffraction center at SLAC National Accelerator Laboratory. These results were complemented by work at the ultrafast electron microscope facility in the Center for Nanoscale Materials (CNM) and the 11-BM and 7-ID beamlines at the Advanced Photon Source (APS).
Implications of the Discovery
The electron spin in a layered antiferromagnet likewise has an impact at longer times than picoseconds. In an earlier research study utilizing APS and CNM facilities, members of the group observed that varying motions of the layers decreased dramatically near the shift from disordered to ordered habits for the electron spins.
” The essential discovery in our current research study was discovering a link in between electron spin and atomic motion that is unique to the layered structure of this antiferromagnet,” Zong said.” And due to the fact that this link manifests at such short time and tiny length scales, we imagine that the capability to control this motion by altering the electromagnetic field or, additionally, by applying a small pressure will have important ramifications for nanoscale gadgets.”
Reference: “Spin-mediated shear oscillators in a van der Waals antiferromagnet” by Alfred Zong, Qi Zhang, Faran Zhou, Yifan Su, Kyle Hwangbo, Xiaozhe Shen, Qianni Jiang, Haihua Liu, Thomas E. Gage, Donald A. Walko, Michael E. Kozina, Duan Luo, Alexander H. Reid, Jie Yang, Suji Park, Saul H. Lapidus, Jiun-Haw Chu, Ilke Arslan, Xijie Wang, Di Xiao, Xiaodong Xu, Nuh Gedik and Haidan Wen, 2 August 2023, Nature.DOI: 10.1038/ s41586-023-06279-y.
Wen, Zong, Xu, and Gedik, other authors include Qi Zhang, Faran Zhou, Yifan Su, Kyle Hwangbo, Xiaozhe Shen, Qianni Jiang, Haihua Liu, Thomas Gage, Donald Walko, Michael E. Kozina, Duan Luo, Alexander Reid, Jie Yang, Suji Park, Saul Lapidus, Jiun-Haw Chu, Ilke Arslan, Xijie Wang and Di Xiao.
This work was primarily supported by the DOE Office of Basic Energy Sciences.
Atomic carpet moved by rushed spins. Shearing of atomic layers in layered iron phosphorus trisulfide is triggered by scrambling of electron spin upon exposure to light pulse. Bought spins on left; rushed spins on. The difference between a ferromagnet and antiferromagnet has to do with a home called electron spin. Reversing the magnetic field reverses the direction of the electron spins.