【Academic Forum】Unique Mechanical-Magnetic Coupling Effects of Carbon Nanostructures
Topic: Unique Mechanical-Magnetic Coupling Effects of Carbon Nanostructures
Lecturer: Zhang Zhuhua, professor and doctoral supervisor of the Institute of Nano Science, Nanjing University of Aeronautics and Astronautics (NUAA)
Host: Ma Zengsheng, doctoral supervisor of XTU School of Materials Science and Engineering
Time: 10:00, December 9 (Sunday), 2018
Venue: Auditorium 319, XTU No. 2 Teaching Building
Zhang Zhuhua got his Ph.D. from NUAA in 2010. He studied joint-education program at the University of Nebraska-Lincoln between 2009 and 2010. He did postdoctoral cooperative research at the Materials Science & Nanoengineering Department, Rice University between 2012 and 2016.
He is currently professor and doctoral supervisor of the NUAA State Key Laboratory of Mechanics and Control of Mechanical Structures. He mainly engaged in the theoretical and computational research of low-dimensional nanomaterial properties and device principles.
He has published 75 SCI papers on international academic journals, including Chem. Soc. Rev. (1), Nature Nanotech. (2), Nature Chem. (1), PRL (1), JACS (4), Nano Lett. (3), Angew Chem. (2), JMPS (2) as first/corresponding author, and other 40 papers received or published on other journals. Five papers were included in the journal cover. His research papers have been cited more than 3,600 times, including more than 2,600 times SCI citations. His works have also been commented on more than 20 times by authoritative academic media such as Nature Nanotechnology and Natural Reviews Materials. In 2012, he won the first prize of the Natural Science of the Ministry of Education. In 2013, he was awarded the National Outstanding Doctoral Dissertation Nomination Award and the first batch of NUAA “Changkong Scholars”.
This report introduces the research progress on the mechanical-magnetic coupling effects of carbon, boron, and nitrogen nanostructures. Firstly, the tight-binding theory for predicting the carbon nanotubes mechanical-electric-magnetic coupling is developed. Through theoretical calculation, it is found that under the coupling of tensile, torsional strain, and magnetic field, the stress can make the carbon nanotubes paramagnetic-diamagnetic change. Based on the bilayer graphene nanoribbons on silicon substrates, the first-principle calculations show that the underlying nanoribbon bond with the substrate and the edge magnetic properties disappear. The weakened interaction between the second and the underlying nanoribbons makes edge magnetic properties intact. By applying a bias voltage to the system, it is found that the graphene nanoribbon edge magnetization linearly changes with the electric field strength. This magnetoelectric effect stems from a new mechanism: bias-driven charge-modulated graphite edge state spin splitting, which is different from the traditional magnetoelectric mechanism and the recently reported magnetoelectric coupling based on the spin-shielding effect. Based on continuum mechanical analysis, it is found that the carbon nanocone can produce a strictly defined strain gradient in the graphene grid under simple loading, and a pseudo-magnetic field of up to 600 T can be achieved by applying only 2% of the vertical strain. This electromechanical coupling is attributed to the unique topology of the cone. Finally, the idea of using the peculiar mechanical-electric-magnetic coupling regulation of low-dimensional structure is introduced. It is found that the most common Si (001) surface can form a spin-polarized hole carrier layer on the surface under the action of the gate voltage. And there is strong ferromagnetic coupling between local magnetic moments. More interestingly, the strained silicon technology can further enhance the ferromagnetism of the Si (001) surface and form a semi-metal electrical transport performance that conducts only a single spin channel.
Organizers: XTU School of Materials Science and Engineering
XTU State-Local Joint Engineering Laboratory of Special Functional Thin Film Materials