邓正副教授 [中国科学院物理研究所]

Title: High-pressure synthesis and effects on several magnetic materials

Language:  Chinese presentation with English slides

Time: 10:00 - 11:00 AM, Monday, April 8, 2024

Place: Onsite：Conference room A417, HPSTAR (Beijing)            Online: Tencent Meeting: https://meeting.tencent.com/dm/4gSUY2PaLuen  Meeting ID: 272-714-913

Host:  Dr. Runze Yu

Abstract:

In my talk, I will introduce two series of magnetic materials, the new type of diluted magnetic semiconductors with independent spin and charge doping and high-pressure stabilized double perovskites. The III-V based DMS materials, such as (Ga, Mn)As, which depends on heterovalent (Ga3+, Mn2+) doping, results in lack of individual control of carrier and spin doping, and seriously limited chemical solubility. They are disadvantages to further improve the Curie temperatures. To overcome these difficulties, a new generation of DMS with independent spin and charge doping have been designed and synthesized. The representatives are I–II–V based Li(Zn,Mn)As and II–II–V based (Ba,K)(Zn,Mn)2As2. (Ba,K)(Zn,Mn)2As2 has the reliable record of Curie temperature of 230 K among DMS where ferromagnetic orderings are mediated by itinerate carriers. The recent advances of the new types of DMS materials including high-pressure effects will be presented.Double perovskite, as another topic, is an excellent platform to explore exotic magnetic properties, owing to two different magnetic cations at B-site. High-pressure synthesis technique is widely used to stabilize the double perovskite structure. We synthesized an exchange bias effect in a double perovskite compound Y2NiIrO6 under 6 ~ 8 GPa and 1500 K. It shows long-range ferrimagnetic ordering (Tc) below 192 K. The robust exchange bias appears at 170 K. It manifests a giant bias field of 1.1 T with a cooling field of only 15 Oe at 5 K. This fascinating exchange bias is attributed to the pinned magnetic moments by the combination of strong spin-orbit coupling on Ir, and antiferromagnetically coupled Ni- and Ir-sublattices. The pinned moments in Y2NiIrO6 are present throughout the full volume rather than those at the interface in conventional bilayers. Afterword, the high-pressure effects were studied by dc magnetization and conduction measurements. Y2NiIrO6 requires the lowest cooling field to induce an equivalent exchange bias field in known single-phase materials, showing substantial potential for applications.References[1] Z. Deng, M. Greenblatt, C. Q. Jin, et al., Advanced Materials 35, 2209759 (2023)[2] Z. Deng, C. Q. Jin, M. Greenblatt, et al., Angew. Chem. Int. Ed. 59, 8240 (2020)[3] Z. Deng, C. Q. Jin, M. Greenblatt, et al., Chem. Mater. 30, 7047 (2018)

Biography of the Speaker: 

Zheng Deng is an associate professor at Institute of Physics, Chinese Academy of Sciences. He received his B.S. in Materials from Harbin Institute of Technology, and Ph.D. in Physics from IOP CAS in 2012. He worked as a postdoc at Greenblatt’s group of Rutgers University from 2014 to 2015. He has been worked on serval types of functional materials for decades, e.g. diluted magnetic semiconductors, perovskites and Fe-based superconductors. He published 20 papers as first- and corresponding-author including Nature Communications, Advanced Materials, Angewandte Chemie, etc.