Magnetoelectric Coupling: Making Single-Molecule Dysprosium Magnets More “obedient”

China Research from energy.people.com.cn

Whether it’s a smart phone with you or a supercomputer deployed in the computer room, having more storage space and capacity is their common technology “dream.” With the deepening of material research, single-molecule magnets have also emerged as the times require, and the use of single-molecule magnets as information storage units to achieve ultra-high-density information storage has become a goal that scientists are striving for.

Big “belly” – with more data storage capacity

Since the first single-molecule magnet Mn12 was first discovered in 1993, the magnetoelectric properties of single-molecule magnets have been deepened. Recently, researchers from the Institute of Physics of the Chinese Academy of Sciences and Nankai University have observed significant magnetic-dielectric effects for the first time in a single-molecule magnet containing rare earth ions (Dy). A few days ago, the reporter interviewed Dr. Wang Yuxia, one of the experimenters and the Department of Chemistry of Nankai University, and listened to her telling the wonderful process of how the electric field can make the single-molecule magnet “obedient” and regulate its magnetic properties.

Big “belly” – with more data storage capacity

Magnetism and electricity are two basic properties of matter. As early as more than 100 years ago, scientists such as Maxwell unified magnetism and electricity in the framework of electrodynamics. Scientists have been trying to explore the coupling of magnetic and electrical properties in solids. Regulation.

The Book of Songs has a cloud that “put me to papaya and report it to Joan”. Scientists have been hoping to see this “harmonious” electromagnetic coupling scene on single-molecule magnets. Wang Yuxia told reporters that the magnetic behavior of single-molecule magnets is manifested by the slow magnetic relaxation of a single molecule. “The so-called relaxation, in layman’s terms, is time.” Seeing the reporter’s face ignorant, Wang Yuxia explained, “It is like a person who is over the mountains, a single-molecule magnet exhibits magnetic behavior, and its electrons also pass through a high slope. While climbing to the other side, usually this will take some time. This time is relaxation.” The reporter learned that due to the high energy levels of rare earth elements, the electrons of single-molecule magnets may “sneak out”. “Line through, so that energy consumption from side to side is less, and the relaxation time is shorter. “These are not conducive to the magnetic properties of single-molecule magnets.” Wang Yuxia said, “Our research hopes to better balance the ‘personality’ of single-molecule magnets and achieve effective and reversible regulation of magnetism through electric fields.”

The orderly controllability of this magneto-electricity means high conversion efficiency, which also means considerable application prospects. “For example, in magnetic storage, magnetic recording has a fast reading speed and slow writing, and ferroelectric recording is complicated to read and write fast. If multi-ferromagnetic materials are used, it is possible to achieve a very high-speed reading and writing process at the same time.” Said.

Broad prospects – storage density is hundreds of times higher than current technology

With the rapid development of wireless communication technology, information storage technology, electromagnetic interference technology, etc., people have put forward higher requirements for material selection and device miniaturization and integration design. The magnetoelectric heterostructure of single-molecule magnet has many advantages such as free conversion of energy between magnetic field and electric field and large magnetoelectric conversion coefficient. Therefore, it has broad application prospects in sensors, multi-state memories and RF microwave devices. In the interview, Wang Yuxia also revealed that they prefer to use chemical synthesis methods to try to introduce iron electrodeization by breaking the spatial inversion symmetry, enhance the magnetoelectric coupling effect, and realize the regulation of the electric or magnetic field on the electric field. Novel magnetoelectric materials that behave as molecular magnets and ferroelectrics.

“Single-molecule magnets show magnetic memory effects as a necessary factor for all data storage. In theory, using single molecules for data storage can provide data densities that are hundreds of times higher than current technologies.” Wang Yuxia said, this also means that single-molecule magnets have Broad application prospects.

At present, the magnetic structure of single-molecule magnets has been relatively clear. Wang Yuxia told reporters that the properties of single-molecule magnets can be predicted initially based on the configuration of the molecule. If the molecule belongs to a symmetrical configuration with large magnetic anisotropy, it is expected to become a single-molecule magnet. The reporter learned that in this experiment, Wang Yuxia and the research partners used the solution slow evaporation method to synthesize the single crystal sample of the rare earth lanthanum monomolecular magnet, which was of the order of millimeters. In this crystal, the strong spin-orbit coupling erbium ions are in a slightly distorted octahedral coordination field, which has uniaxial anisotropy, which is favorable for the formation of single-molecule magnets. The low temperature magnetic relaxation behavior and magnetic anisotropy of the single molecule magnet were determined by measurement of AC susceptibility and DC magnetization. This research also laid a solid foundation for subsequent electrical continuous measurement observations. (Reporter Sun Yusong)

(Editor: Wang Shaoshao, He Yingchun)

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