Spectroscopic and Local Magnetic Measurements in High-Spin Molecular Nanomagnets

分子磁体包含大量(几乎)完全相同的磁团簇，总自旋约为10个数量级。这些纳米磁体介于经典磁学和量子磁学之间，有望用于高密度信息存储，并可能用于量子计算。本项目的目标是加深对班级中典型成员MN-12的了解。(1)将利用同步辐射在非常宽的频率范围内进行高分辨率光谱测量；目的是调查磁团簇的内部自由度，并研究将产生有关无序、内部磁场和电子-声子耦合强度的信息的线宽和线形；(2)将研究磁雪崩以确定它们是否如最近建议的那样伴随着相干超辐射发射；(2)将使用微霍尔棒探测器来研究在受控条件下和在磁雪崩期间磁化弛豫趋于平衡时材料内部自旋反转的局部空间和时间演变。参与实验室的前沿研究为研究生和本科生提供高水平的教育和培训。应该指出的是，城市学院的本科生来自各个经济阶层和不同的民族和种族背景。分子纳米磁体，有时被称为单分子磁体，是高密度信息存储和量子计算的潜在候选者。量子计算是一种全新的、基于量子现象的计算范式。量子计算机的量子力学元素，也就是量子比特，不是有两种可能的“经典”值，而是0或1，它们代表了更广泛的可能性，使计算能力更强。目前提议的目标是更深入地了解这类材料的原型成员--醋酸锰，它由大量相同的12个锰原子组成的团簇组成，形成规则排列在有机晶体中的磁性分子；每个分子都是一个小磁铁，相当于一个电子的磁性20倍。将在布鲁克海文的同步加速器光源上进行低温光谱研究，并将在纽约城市学院使用非常小的霍尔棒测量长度为微米级的低温局部磁化强度。参与实验室的前沿研究为研究生和本科生提供高水平的教育和培训。应该指出的是，城市学院的本科生来自各个经济阶层和非常不同的民族和种族背景

Molecular magnets contain a large number of (nearly) identical magnetic clusters of total spin on the order of 10. Borderline between classical and quantum magnetism, these nanomagnets hold promise for high-density information storage and, possibly, quantum computation. The goal of the present project is to gain a deeper understanding of Mn-12, a prototypical member of the class. (1) High resolution spectroscopic measurements will be performed using synchrotron radiation over a very broad range of frequencies; the aim is to investigate the internal degrees of freedom of the magnetic clusters and to study the line-widths and line shapes which will yield information regarding disorder, internal magnetic fields and electron-phonon coupling strengths; magnetic avalanches will be studied to determine whether they are accompanied by coherent super-radiant emission, as has been recently suggested; (2) Micro-Hall bar detectors will be used to investigate the local spatial and temporal evolution of spin reversal inside the material as the magnetization relaxes toward equilibrium under controlled conditions and during magnetic avalanches. Participation in forefront research in the laboratory provides high-level education and training for both graduate and undergraduate students. It should be noted that City College draws its undergraduate student population from every economic stratum and from diverse ethnic and racial backgrounds. %%% Molecular nanomagnets, sometimes referred to as "single molecule magnets" are potential candidates for high-density information storage and quantum computation. Quantum computation is a new and entirely different computing paradigm based on quantum phenomena. Rather than having two possible "classical" values, 0 or 1, the quantum mechanical elements of quantum computers, called "qubits", represent a far broader set of possibilities, enabling much greater computing power. The goal of the current proposal is to gain a deeper understanding of a prototypical member of this class of materials, Mn12-acetate, which consists of a very large number of identical clusters of 12 manganese atoms that form magnetic molecules regularly arranged in an organic crystal; each molecule is a little magnet that is equivalent to 20 times the magnetism of a single electron. Spectroscopic studies will be performed at low temperatures at the synchrotron light source at Brookhaven, and measurements will be taken at City College of New York of the local magnetization at low temperatures on a length scale of microns using very small Hall bars. Participation in forefront research in the laboratory provides high-level education and training for both graduate and undergraduate students. It should be noted that City College draws its undergraduate student population from every economic stratum and from very diverse ethnic and racial backgrounds