Development of Room-Temperature Molecular/Organic Ferromagnets and Estimation of Their Low-Frequency Shielding Materials

三年前，我们发现了TCNQ或TCNQF_4与TCNQF_4自由基阴离子1：2混合盐中的室温铁磁行为。在二乙基取代的TCNQ或四氰基萘基喹二甲烷与其自由基阴离子的1：2混合盐中也发现了类似的行为。这一观察结果是相当值得注意的，因为迄今为止所获得的纯有机铁磁体和弱铁磁体的自旋有序化最高温度为36K。然而，在这些1：2摩尔盐中观察到的饱和磁化强度仅为1个S=1/2自旋/公式单位所得值(5,580 emu·mol^&lt；-1&gt；)的0.1%。对于1：2的二甲基三氰胺及其自由基阴离子的混合盐，观察到了金属般的高导电性和室温铁磁行为。因此，这种混合盐可以被视为铁、钴和镍等铁磁性金属的类似物。人们对导电pi电子和定域d自旋之间的相互作用很感兴趣，而这种混合盐是一个既包含导电pi电子又包含定域pi自旋的新的分子体系。综上所述，在TCNQ、取代TCNQ和TCNQ类似物的1：2混合盐中可以观察到共同的室温铁磁行为，但自旋有序化的机理仍未被阐明。为了阐明自旋有序化的机理和寻找具有更大饱和磁化强度的室温(铁)磁体，还需要进一步的研究。

Three years ago we found out room-temperature ferromagnetic behavior in 1 : 2 mixed salts of TCNQ or TCNQF_4 with TCNQF_4 radical anion. The similar behavior was also recognized in 1 : 2 mixed salts of diethyl-substituted TCNQ or tetracyanonaphthoquinodimethane with their radical anions. This observation is quite remarkable, since the highest temperature of spin ordering is 36 K for purely organic ferromagnets and weak ferromagnets obtained so far. However, the saturation magnetization observed in these 1 : 2 mized salts is only 0.1% of the value (5,580 emu.mol^<-1>) obtained by one S=1/2 spin per formula unit.For the 1 : 2 mixed salt of dimethyl-substituted TCNQ with its radical anion, metal-like high electrical conductivity was observed together with room-temperature ferromagnetic behavior. Accordingly, this mixed salt can be regarded as an analogue to a ferromagnetic metal such as iron, cobalt and nickel. Much interest is directed toward the interaction between the interaction between conducting pi electron and localized d spin, while this mixed salt should be noted as a new molecular system involving both conducting pi electron and localized pi spin.In summary, room-temperature ferromagnetic behavior can be in common observed in 1 : 2 mixed salts of TCNQ, substituted TCNQ's and TCNQ analogue, but the mechanism of spin ordering remains to be still not elucidated. Further study is necessary in order to elucidate the mechanism of spin ordering and to search a room-temperature (ferro)magnet with larger saturation magnetization.