Spectroscopic and Local Magnetic Measurements in High-Spin Molecular Nanomagnets

Cuny City College, New York NY

Investigators

Abstract

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