Scientists at Purdue University have actually advanced this field by introducing quantum spin into twisted double bilayers of antiferromagnets, leading to tunable moiré magnetism. Credit: SciTechDaily.comPurdue quantum scientists twist double bilayers of an antiferromagnet to demonstrate tunable moiré magnetism.Twistronics isnt a brand-new dance move, workout devices, or brand-new music fad. It is an exciting brand-new development in quantum physics and product science where van der Waals materials are stacked on top of each other in layers, like sheets of paper in a ream that can quickly twist and rotate while remaining flat, and quantum physicists have utilized these stacks to discover intriguing quantum phenomena.Adding the principle of quantum spin with twisted double bilayers of an antiferromagnet, it is possible to have tunable moiré magnetism.”The moiré superlattice structure of twisted double bilayer (tDB) CrI3 and its magnetic behaviors probed by the magneto-optical-Kerr-effect (MOKE). Such a moiré magnetism is a novel type of magnetism featuring spatially varying ferromagnetic and antiferromagnetic phases, alternating occasionally according to the moiré superlattice.
Twistronics, an unique field in quantum physics, includes stacking van der Waals materials to explore brand-new quantum phenomena. Scientists at Purdue University have actually advanced this field by introducing quantum spin into twisted double bilayers of antiferromagnets, causing tunable moiré magnetism. This development recommends brand-new products for spintronics and promises developments in memory and spin-logic devices. Credit: SciTechDaily.comPurdue quantum researchers twist double bilayers of an antiferromagnet to show tunable moiré magnetism.Twistronics isnt a brand-new dance relocation, exercise equipment, or brand-new music trend. No, its much cooler than any of that. It is an amazing brand-new development in quantum physics and material science where van der Waals materials are stacked on top of each other in layers, like sheets of paper in a ream that can easily twist and turn while staying flat, and quantum physicists have actually used these stacks to find interesting quantum phenomena.Adding the principle of quantum spin with twisted double bilayers of an antiferromagnet, it is possible to have tunable moiré magnetism. This recommends a new class of material platform for the next step in twistronics: spintronics. This new science might result in appealing memory and spin-logic devices, opening the world of physics as much as a whole new opportunity with spintronic applications.By twisting a van der Waals magnet, non-collinear magnetic states can emerge with substantial electrical tunability. Credit: Ryan Allen, Second Bay StudiosA team of quantum physics and products scientists at Purdue University has presented the twist to manage the spin degree of liberty, utilizing CrI3, an interlayer-antiferromagnetic-coupled van der Waals (vdW) material, as their medium. They have published their findings, “Electrically tunable moiré magnetism in twisted double bilayers of chromium triiodide,” in Nature Electronics.”In this study, we fabricated twisted double bilayer CrI3, that is, bilayer plus bilayer with a twist angle between them,” says Dr. Guanghui Cheng, co-lead author of the publication. “We report moiré magnetism with abundant magnetic stages and substantial tunability by the electrical method.”The moiré superlattice structure of twisted double bilayer (tDB) CrI3 and its magnetic habits penetrated by the magneto-optical-Kerr-effect (MOKE). Section a above shows the schematic of moiré superlattice produced by interlayer twisting. Bottom panel: a non-collinear magnetic state can emerge. Section b above shows MOKE results reveal the coexistence of antiferromagnetic (AFM) and ferromagnetic (FM) orders in the “moiré magnet” tDB CrI3 compared to the AFM orders in natural antiferromagnetic bilayer CrI3. Credit: Illustration by Guanghui Cheng and Yong P. Chen”We stacked and twisted an antiferromagnet onto itself and voila got a ferromagnet,” states Chen. “This is likewise a striking example of the recently emerged location of twisted or moiré magnetism in twisted 2D products, where the twisting angle between the two layers offers an effective tuning knob and changes the material residential or commercial property drastically.””To produce twisted double bilayer CrI3, we wreck one part of bilayer CrI3, rotate and stack onto the other part, utilizing the so-called tear-and-stack method,” discusses Cheng. “Through magneto-optical Kerr result (MOKE) measurement, which is a sensitive tool to probe magnetic behavior down to a couple of atomic layers, we observed the coexistence of ferromagnetic and antiferromagnetic orders, which is the trademark of moiré magnetism, and even more demonstrated voltage-assisted magnetic switching. Such a moiré magnetism is an unique type of magnetism featuring spatially differing ferromagnetic and antiferromagnetic stages, alternating occasionally according to the moiré superlattice.”Twistronics as much as this point have primarily focused on regulating electronic residential or commercial properties, such as twisted bilayer graphene. The Purdue team desired to present the twist to spin degree of freedom and selected to utilize CrI3, an interlayer-antiferromagnetic-coupled vdW material. The outcome of stacked antiferromagnets twisting onto itself was enabled by having produced samples with different twisting angles. In other words, when made, the twist angle of each device ends up being set, and then MOKE measurements are performed.Theoretical calculations for this experiment were carried out by Upadhyaya and his group. This offered strong support for the observations showed up at by Chens team.”Our theoretical estimations have actually revealed a rich stage diagram with non-collinear stages of TA-1DW, TA-2DW, TS-2DW, TS-4DW, etc,” says Upadhyaya.This research folds into a continuous research avenue by Chens group. This work follows several associated current publications by the group associated to novel physics and properties of “2D magnets,” such as “Emergence of electric-field-tunable interfacial ferromagnetism in 2D antiferromagnet heterostructures,” which was just recently released in Nature Communications. This research study avenue has interesting possibilities in the field of spintronics and twistronics.”The identified moiré magnet suggests a brand-new class of product platform for spintronics and magnetoelectronics,” says Chen. “The observed voltage-assisted magnetic changing and magnetoelectric result may result in promising memory and spin-logic gadgets. As an unique degree of flexibility, the twist can be suitable to the vast range of homo/heterobilayers of vdW magnets, opening the chance to pursue new physics along with spintronic applications.”Reference: “Electrically tunable moiré magnetism in twisted double bilayers of chromium triiodide” by Guanghui Cheng, Mohammad Mushfiqur Rahman, Andres Llacsahuanga Allcca, Avinash Rustagi, Xingtao Liu, Lina Liu, Lei Fu, Yanglin Zhu, Zhiqiang Mao, Kenji Watanabe, Takashi Taniguchi, Pramey Upadhyaya and Yong P. Chen, 19 June 2023, Nature Electronics.DOI: 10.1038/ s41928-023-00978-0The group, mainly from Purdue, has 2 equal-contributing lead authors: Dr. Guanghui Cheng and Mohammad Mushfiqur Rahman. Cheng was a postdoc in Dr. Yong P. Chens group at Purdue University and is now an Assistant Professor in Advanced Institute for Material Research (AIMR, where Chen is also associated as a primary private investigator) at Tohoku University. Mohammad Mushfiqur Rahman is a PhD student in Dr. Pramey Upadhyayas group. Both Chen and Upadhyaya are matching authors of this publication and are professors at Purdue University. Chen is the Karl Lark-Horovitz Professor of Physics and Astronomy, a Professor of Electrical and Computer Engineering, and the Director of Purdue Quantum Science and Engineering Institute. Upadhyaya is an Assistant Professor of Electrical and Computer Engineering. Other Purdue-affiliated team members include Andres Llacsahuanga Allcca (PhD student), Dr. Lina Liu (postdoc), and Dr. Lei Fu (postdoc) from Chens group, Dr. Avinash Rustagi (postdoc) from Upadhyayas group and Dr. Xingtao Liu (former research assistant at Birck Nanotechnology Center). This work is partly supported by United States Department of Energy (DOE) Office of Science through the Quantum Science Center (QSC, a National Quantum Information Science Research Center) and Department of Defense (DOD) Multidisciplinary University Research Initiatives (MURI) program (FA9550-20-1-0322). Cheng and Chen also got partial support from WPI-AIMR, JSPS KAKENHI Basic Science A (18H03858), New Science (18H04473 and 20H04623), and Tohoku University FRiD program in early stages of the research.Upadhyaya also acknowledges support from the National Science Foundation (NSF) (ECCS-1810494). Bulk CrI3 crystals are provided by the group of Zhiqiang Mao from Pennsylvania State University under the assistance of the US DOE (DE-SC0019068). Bulk hBN crystals are offered by Kenji Watanabe and Takashi Taniguchi from National Institute for Materials Science in Japan under support from the JSPS KAKENHI (Grant Numbers 20H00354, 21H05233 and 23H02052) and World Premier International Research Center Initiative (WPI), MEXT, Japan.
