Graduate student Lebing Chen displays chromium triiodide crystals he made in a Rice University lab. Stacked layers of atomically thin 2D chromium triiodide have unusual electronic and magnetic homes that might prove beneficial for “spintronic” innovations that encode information in the spins of electrons. In van der Waals products, atomically thin 2D layers are stacked like pages in a book. A single 2D sheet of chromium triiodine has the same sort of magnetic order that makes magnetic decals stick to a metal fridge. Stacks of 3 or more 2D layers also have that magnetic order, which physics call ferromagnetic.
Spin is an intrinsic function of quantum things and the spins of electrons play a key function in bringing about magnetism.
Rice physicist Pengcheng Dai, co-corresponding author of the PRX study, said inelastic neutron-scattering experiments on the 2D material chromium triiodine validated the origin of the topological nature of spin excitations, called magnons, that his group and others found in the material in 2018.
Graduate student Lebing Chen displays chromium triiodide crystals he made in a Rice University laboratory. Stacked layers of atomically thin 2D chromium triiodide have uncommon electronic and magnetic residential or commercial properties that could show helpful for “spintronic” innovations that encode information in the spins of electrons. Credit: Jeff Fitlow/Rice University
The groups latest experiments at Oak Ridge National Laboratorys (ORNL) Spallation Neutron Source revealed “spin-orbit coupling causes uneven interactions in between spins” of electrons in chromium triiodine, Dai stated. “As an outcome, the electron spins feel the magnetic field of moving nuclei in a different way, and this impacts their topological excitations.”
In van der Waals products, atomically thin 2D layers are stacked like pages in a book. The atoms within layers are securely bonded, but the bonds between layers are weak. The materials are beneficial for exploring unusual electronic and magnetic behaviors. A single 2D sheet of chromium triiodine has the same sort of magnetic order that makes magnetic decals stick to a metal fridge. Stacks of 3 or more 2D layers also have that magnetic order, which physics call ferromagnetic. 2 stacked sheets of chromium triiodine have an opposite order called antiferromagnetic.
Rice University physicists Pengcheng Dai (left) and Lebing Chen have found that uncommon magnetic functions they formerly saw in 2D chromium triiodide arise from topological features. Credit: Jeff Fitlow/Rice University
That weird habits led Dai and coworkers to study the material. Rice graduate trainee Lebing Chen, the lead author of this weeks PRX study and of the 2018 research study in the same journal, developed methods for making and lining up sheets of chromium triiodide for experiments at ORNL. By bombarding these samples with neutrons and measuring the resulting spin excitations with neutron time-of-flight spectrometry, Chen, Dai and colleagues can determine unknown functions and behaviors of the product.
In their previous research study, the scientists showed chromium triiodine makes its own electromagnetic field thanks to magnons that move so quickly they feel as if they are moving without resistance. Dai stated the latest study explains why a stack of 2 2D layers of chromium triiodide has antiferromagnetic order.
” We discovered proof of a stacking-dependent magnetic order in the product,” Dai stated. Finding the origins and key features of the state is crucial since it could exist in other 2D van der Waals magnets.
Referral: “Magnetic Field Effect on Topological Spin Excitations in CrI3” by Lebing Chen, Jae-Ho Chung, Matthew B. Stone, Alexander I. Kolesnikov, Barry Winn, V. Ovidiu Garlea, Douglas L. Abernathy, Bin Gao, Mathias Augustin, Elton J. G. Santos, and Pengcheng Dai, 31 August 2021, Physical Review X.DOI: 10.1103/ PhysRevX.11.031047.
Extra co-authors consist of Bin Gao of Rice, Jae-Ho Chung of Korea University, Matthew Stone, Alexander Kolesnikov, Barry Winn, Ovidiu Garlea and Douglas Abernathy of ORNL, and Mathias Augustin and Elton Santos of the University of Edinburgh.
The research was moneyed by the National Science Foundation (1700081 ), the Welch Foundation (C-1839), the National Research Foundation of Korea (2020R1A5A1016518, 2020K1A3A7A09077712), the United Kingdoms Engineering and Physical Research Council and the University of Edinburgh and utilized centers provided by the United Kingdoms ARCHER National Supercomputing Service and the Department of Energys Office of Science.
Rice University graduate student Lebing Chen used a high-temperature heater to make chromium triiodide crystals that yielded the 2D products for experiments at Oak Ridge National Laboratorys Spallation Neutron Source. Credit: Jeff Fitlow/Rice University
Topological feature might prove beneficial for encoding info in electron spins.
Rice physicists have actually validated the topological origins of magnons, magnetic features they found three years back in a 2D product that could prove useful for encoding details in the spins of electrons.
The discovery, described in a study published online just recently in the American Physical Society journal Physical Review X, supplies a new understanding of topology-driven spin excitations in materials called in 2D van der Waals magnets. The products are of growing interest for spintronics, a movement in the solid-state electronic devices neighborhood towards innovations that use electron spins to encode info for computation, storage, and communications.