AVS 56th International Symposium & Exhibition
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI-FrM

Invited Paper MI-FrM9
Perspectives in Multi-Functional Single-Molecule Magnets and Single-Chain Magnets

Friday, November 13, 2009, 11:00 am, Room C1

Session: Molecular/Organic Based Magnetism
Presenter: M. Yamashita, Tohoku University, Japan
Correspondent: Click to Email
Recently, the quantum molecular nano-magnets have been attracting much attention from the viewpoints of the basic sciences as well as the applied sciences such as memory storages, quantum computers, etc. So far more than 300 single-molecule quantum magnets have been reported, while about 20 types of single-chain quantum magnets have been reported. They have several interesting themes to be resolved as follows: (1) High blocking temperature, (2) Quantum GMR, (3) Memory storage into one quantum molecule magnet, (4) Quantum computer, (5) Quantum FET, (6) Glauber dynamics, (7) Multi-functionalities, (8) Kondo effect, etc.

 

As for (1), since the potential barrier of the double wells is defined as DS2 and (8J+D)S2 for the single-molecule magnets and single-chain magnets, respectively, we must increase the D, S, and J parameters to raise the blocking temperatures of these compounds. However, the control of the parameter D is very difficult. Then, we propose the conducting quantum molecular magnets. By the interaction between conducting electrons and localized quantum molecule magnets, the coherence among the quantum molecule magnets is strengthened and then the spin flips are made difficult, resulting in raising the blocking temperature. According to such a strategy, we have synthesized three types of conducting single-molecule magnets such as [Mn4(hmp)6(MeCN)2][Pt(mnt)2]6, [Mn2(5-MeOsaltmen)2(MeCN)2][Ni(dmit)]7(MeCN), and [Mn2(5-Rsaltmen)2][Ni(dmit)2]2. As for (2), since in the quantum molecular magnets, we can create artificially the large spin numbers such as S =10, 20, 30, etc, we can anticipate new quantum GMR phenomena by interacting between large S and conducting electrons. According to such a strategy, we try to synthesize a metallic single-molecule magnet. Otherwise, we have a plan to occur a photo-induced phase transition from semiconductor to metallic state in conducting single-molecule magnet. As for (3), we have accessed to one single-molecule magnet of Pc2Tb by STM. We have a plane to input one memory into one single-molecule magnet and output it from one single-molecule magnet by using spin-polarized STM. We have observed Kondo Effect at 4.8 K in this compound by STS for the first time. As for (7), we have synthesized the single-molecule magnet with photo-induced switching and the single-chain magnet with absorption and desorption of crystal solvents reversibly like a spo