Synthesis and characterization of molecular materials showing slow magnetic relaxation and magnetic memory effect

该项目涉及在缺乏长程磁序的情况下存在磁滞这一相对新颖的现象的研究。这一研究领域由申请人在近十年前开辟，发现由12个强耦合的顺磁性金属离子组成的分子簇在基态中表现出非常缓慢的磁弛豫(Sessoli等人)。自然1993、365、141)。申请人还参与了一个相关领域的研究，即在链之间没有相互作用的情况下，在严格的一维材料中存在磁化的缓慢弛豫。这种现象几乎在四十年前就被预测到了(格劳伯J.数学)。太棒了。1963、4、294-307)，但直到最近才被申请人首次观察到(Caneschi等人)。安吉。化学。实习医生。艾德。2001、40、1760-1763)。为了更好地理解这一新现象，该项目将主要关注其他一维磁性材料的合成和表征，这些材料表现出缓慢的磁弛豫。将通过掺杂链的合成和表征来研究链间相互作用以及缺陷(有限链效应)的存在所起的作用。这项研究的第二个方面将是研究以强各向异性相互作用为特征的零d材料(团簇)中的滞后行为。

The project concerns the study of the relatively novel phenomenon of the presence of magnetic hysteresis in the absence of long range magnetic order. This field of research has been opened by the applicant almost ten years ago with the discovery that a molecular cluster comprising twelve paramagnetic metal ions strongly coupled to give a large spin in the ground state show very slow magnetic relaxation at low temperature (Sessoli et al. Nature 1993, 365, 141). The applicant has also been involved in a related area of research, i. e. the existence of slow relaxation of the magnetization in strictly one-dimensional material in the absence of interactions between the chains. Such a phenomenon has been predicted almost forty years ago (Glauber J. Math. Phys. 1963, 4, 294-307) but only recently observed for the first time by the applicant (Caneschi et al. Angew. Chem. Intern. Ed. 2001, 40, 1760-1763). The project will mainly focus on the synthesis and characterization of other 1-d magnetic material exhibiting slow magnetic relaxation, in order to better understand this new phenomenon. The role played by the inter-chain interactions, as well as the presence of defects (finite chain effects) will be investigated through the synthesis and characterization of doped chains. A second aspect of this research will be the investigation of hysteretic behavior in zero-d materials (clusters) characterized by strongly anisotropic interactions.