Experimental studies on magnetic interaction and anisotropy in 3d-4f heterometallic systems

3d-4f异金属体系中磁相互作用和各向异性的实验研究

• 批准号: 415157846
• 负责人: Dr. Changhyun Koo
• 金额: --
• 依托单位: Department of Chemistry
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/415157846?language=en
• 关键词: Experimental; studies; magnetic; interaction; anisotropy

Single molecular magnets (SMMs) attract lots of attention as zero-dimensional quantum magnetic systems and potential candidates for quantum storage applications. Since the main characteristic of SMMs is induced by the magnetic anisotropy barrier, many efforts focus on the enlargement of magnetic anisotropy of the SMM candidate complexes. So far many complexes involving 3d transition metal ions have been studied because 3d ions show a reasonable anisotropy induced by spin-orbit coupling and ligand field, and they may evolve strong exchange coupling. However, orbital quenching in 3d transition metal ions causes a limit of magnetic anisotropy. Recently, lanthanides where unquenched orbital moments provide large spin-orbit coupling and strong anisotropy have been suggested for improved SMMs. One of the disadvantages of 4f complexes is weak magnetic exchange coupling which induces fast relaxation of magnetization even though large anisotropy barrier is raised. Moreover, magnetic tunneling at zero-magnetic field in weakly coupled SMM complexes is a critical deficient for quantum storage applications. In order to overcome these issues, 3d-4f heterometallic complexes are suggested as the extended 3d orbitals in transition metal ions can yield enhanced coupling strengths. However, for these systems magneto-structural correlations for optimizing magnetic exchange and magnetic anisotropy are not yet well developed. In the project at hand, relevant magnetic parameters, such as 3d-4f magnetic coupling and magnetic anisotropy, will be experimentally studied on a variety of 3d-4f complexes. The main experimental method will be tunable high-frequency/high-field electron paramagnetic resonance (EPR) spectroscopy which will be accompanied by static and pulsed field magnetization measurements. To be specific, Fe2Ln2 (Ln = Dy, Gd, Y), CrDy6, Fe10Ln10 (Ln = Gd, Y), various Co2Dy2 (plus Co2Y2 and Zn2Dy2), Cu4Ln4 (Ln = Dy, Y), Ni2Ln2 (Ln = Dy, Tb, Ho, Lu) and Ln monomers with triangular arranged radicals (Ln = Y, Gd, Dy) provided by synthetic chemistry groups for this project will be studied in order to precisely determine the strength of 3d-4f magnetic interaction as well as magnetic anisotropy. Comparison with Ln = Gd,Y provides information on the anisotropy size and type and on magnetic interaction in the 3d-subsystems. Collaboration with theorists will yield magneto-structural correlations, aiming at determining routes to maximize the exchange interaction between 3d and 4f moments. We will work out general principles describing the relation between the exchange interaction and effective barrier of the complexes. Depending on the cw-EPR results of promising complexes (e.g. Dy6Cr) T1- and T2-relaxation times will be studied in order to determine their spin dynamics and to exploit their potential for quantum device applications.

单分子磁体作为零维量子磁系统和量子存储的潜在候选体，受到了广泛的关注。由于SMM的主要特性是由磁各向异性势垒引起的，因此许多研究都集中在扩大SMM候选配合物的磁各向异性上。由于三维过渡金属离子在自旋轨道耦合和配体场的作用下表现出合理的各向异性，并可能演化为强交换耦合，因此目前研究了许多涉及三维过渡金属离子的配合物。然而，在三维过渡金属离子中，轨道猝灭会导致磁各向异性的限制。近年来，镧系元素的非淬火轨道矩提供了大的自旋轨道耦合和强的各向异性，被建议用于改进的smm。4f配合物的缺点之一是磁交换耦合弱，即使产生较大的各向异性势垒，也会引起磁化的快速弛豫。此外，弱耦合SMM配合物在零磁场下的磁隧穿是量子存储应用的关键缺陷。为了克服这些问题，我们提出了3d-4f异质金属配合物，因为过渡金属离子中扩展的3d轨道可以产生增强的耦合强度。然而，对于这些系统，优化磁交换和磁各向异性的磁结构相关性尚未得到很好的发展。本项目将在多种3d-4f配合物上实验研究3d-4f磁耦合、磁各向异性等相关磁参数。主要的实验方法将是可调谐高频/高场电子顺磁共振（EPR）光谱，并伴有静态和脉冲场磁化测量。具体而言，为了精确确定3d-4f磁相互作用的强度和磁各向异性，本项目将研究由合成化学小组提供的Fe2Ln2 （Ln = Dy, Gd， Y）、CrDy6、Fe10Ln10 （Ln = Gd， Y）、各种Co2Dy2（加上Co2Y2和Zn2Dy2）、Cu4Ln4 （Ln = Dy， Y）、Ni2Ln2 （Ln = Dy, Tb, Ho, Lu）和具有三角形排列自由基（Ln = Y, Gd, Dy）的Ln单体。与Ln = Gd相比，Y提供了三维子系统中各向异性大小和类型以及磁相互作用的信息。与理论学家的合作将产生磁结构相关性，旨在确定最大化3d和4f力矩之间交换相互作用的路线。我们将得出描述配合物的交换相互作用与有效势垒之间关系的一般原理。根据有前途的配合物（例如Dy6Cr）的cw-EPR结果，将研究T1-和t2 -弛豫时间，以确定它们的自旋动力学并利用它们在量子器件应用中的潜力。

项目成果

Role of Coordination Geometry on the Magnetic Relaxation Dynamics of Isomeric Five-Coordinate Low-Spin Co(II) Complexes.

• DOI: 10.1021/acs.inorgchem.1c02881
• 发表时间: 2021-12
• 期刊: Inorganic chemistry
• 影响因子: 4.6
• 作者: L. Spillecke;Shalini Tripathi;C. Koo;Arne Bahr;Abinash Swain;Rajashi Haldar;Mursaleem Ansari;J. Jasinski;G. Rajaraman;M. Shanmugam;R. Klingeler

High-frequency EPR study on Cu4Cu- and Co4Co-metallacrown complexes

Cu4Cu-和Co4Co-金属冠配合物的高频EPR研究

• DOI: 10.1016/j.jmmm.2019.01.038
• 发表时间: 2019
• 期刊: Journal of Magnetism and Magnetic Materials
• 影响因子: 2.7
• 作者: C. Koo;J. Park;J. Butscher;E. Rentschler;R. Klingeler
• 通讯作者: R. Klingeler

Magnetic behavior of the novel pentagonal-bipyramidal erbium(III) complex (Et3NH)[Er(H2DAPS)Cl2]: high-frequency EPR study and crystal-field analysis.

新型五角双锥铒(III)络合物(Et3NH)[Er(H2DAPS)Cl2]的磁性行为：高频EPR研究和晶体场分析

• DOI: 10.1039/d1dt03228c
• 发表时间: 2021
• 期刊: Dalton transactions
• 影响因子: 4
• 作者: L. Spillecke;C. Koo;O. Maximova;V. S. Mironov;V. A. Kopotkov;D. V. Korchagin;A. N. Vasiliev;E. B. Yagubskii;R. Klingeler
• 通讯作者: R. Klingeler

A high-frequency EPR study of magnetic anisotropy and intermolecular interactions of Co(II) ions

• DOI: 10.1016/j.poly.2021.115389
• 发表时间: 2021-11
• 期刊: Polyhedron
• 影响因子: 2.6
• 作者: L. Spillecke;Shalini Tripathi;C. Koo;Mursaleem Ansari;S. Vaidya;Amaleswari Rasamsetty;T. Mallah