金属富勒烯单分子磁体  

Endohedral metallofullerene single molecule magnets

作　　者：官润南 陈木青[1] 杨上峰[1] Runnan Guan;Muqing Chen;Shangfeng Yang(CAS Key Laboratory of Materials for Energy Conversion,Hefei National Laboratory for Physical Sciences at Microscale,Department of Materials Science and Engineering,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]中国科学技术大学材料科学与工程系,合肥微尺度物质科学国家研究中心,中国科学院能量转换材料重点实验室,合肥230026

出　　处：《科学通报》2020年第21期2209-2224,共16页Chinese Science Bulletin

基　　金：国家自然科学基金(51925206)资助。

摘　　要：金属富勒烯是一类碳笼内部嵌入了金属离子或者金属团簇的富勒烯.当内嵌的金属离子含有未成对电子时,金属富勒烯具有顺磁性,而内嵌的金属团簇则形成了特殊的配位场,使得金属富勒烯表现出单分子磁体性质.基于金属富勒烯稳定性高、分子结构易于调控的优点,近年来金属富勒烯在单分子磁体领域崭露头角.自2012年首例内嵌氮化物金属富勒烯单分子磁体被报道以来,金属富勒烯单分子磁体的种类已扩展到内嵌碳化物金属富勒烯、氧化物金属富勒烯、硫化物金属富勒烯、氰化物金属富勒烯和双金属富勒烯等.本文首先简单介绍了金属富勒烯的结构特点,然后详细总结了目前报道的所有金属富勒烯单分子磁体,并通过对比不同类型的金属富勒烯单分子磁体的性能,讨论了影响金属富勒烯单分子磁体性质的因素,最后对金属富勒烯单分子磁体的发展前景进行展望.Nanoscale magnetic materials have been attracting enormous interests during the past few decades due to the rapid development of high-density magnetic storage devices.A breakthrough in nanomagnetism is the discovery of single molecule magnets(SMMs),which exhibit slow relaxation and quantum tunneling of the magnetization resulted from a molecular-based blocking anisotropy,and thus have Potential applications in high-density data storage,molecular spintronics and quantum computing.Since the report of Mn12-complex as the first SMM by Sessoli et al.in 1993,a large number of SMMs based on organometallic coordination compounds have been synthesized.Compared to the traditional bulk magnets,the magnetic properties of SMMs are determined by their instrinsic spin structures resulting in slow magnetic relaxation.SMM is characterized by a bi-stable magnetic ground state and a certain spin-reversal barrier(Ueff).Additionally,hysteresis loops can be observed below the blocking temperature(TB).Therefore,SMMs with excellent magnetic properties always have high TB and Ueff.Ueff Ueff depends strongly on spin ground state(S)and magneto-crystalline anisotropy(D),and can be expressed with the formula Ueff=|D|S2.For transition metal-based SMMs,their low magnetocrystalline anisotropies(D)result in relative low Ueff.In recent years,lanthanide based SMMs have been studied intensively and become the most promising high-performance SMMs,owning to their strong single ion anisotropy.Encapsulating metal atoms or metallic clusters into fullerene cages generate a special class of fullerenes,the so-called endohedral metallofullerenes(EMFs),for which the encapsulation of metal atoms endow EMFs more fascinating properties compared to empty fullerenes.For instance,EMFs are paramagnetic when the entrapped metal ions have unpaired electrons.Furthermore,EMFs were able to show excellent SMM properties when the encapsulated clusters induce appropriate ligand-fields.EMFs with lanthanide open up a new avenue in the field of SMMs in 2012 when single molecu

关 键 词：富勒烯 金属富勒烯 单分子磁体 稀土金属 团簇 

分 类 号：O641.3[理学—物理化学]