FRG: NIRT: Quantum Spin Dynamics in Molecular Nanomagnets

New York University, New York NY

Investigators

Abstract

****NON-TECHNICAL ABSTRACT**** This award results from a proposal received in response to Nanoscale Science and Engineering initiative, NSF 04-043, category NIRT. It supports an interdisciplinary research effort that will investigate the quantum dynamics of chemically synthesized magnetic nanostructures. The miniaturization of magnetic devices to this size is critical to advances in magnetic information processing, which is an important industry in the United States. Conventional techniques used to fabricate magnetic nanostructures have serious limitations. For this reason, there is a growing interest in chemical syntheses that provide a bottom-up or molecule-based approach to the assembly of magnetic nanostructures--often, with atomic scale control of magnetic structure. This project will focus on the magnetization dynamics and how the environment of the nanomagnet affects these dynamics. For a large magnet, this coupling leads to energy dissipation or magnetic friction. For magnetic nanostructures the environment also leads to the loss of quantum information, known as decoherence. An important aim of this project is to understand the microscopic mechanisms of energy dissipation and decoherence in nanomagnets, and to develop synthetic strategies to mitigate certain environmental effects, such as decoherence. Chemical synthesis of magnetic nanostructures will be combined with advanced magnetic measurement techniques, which include high-speed high-sensitivity magnetometry, magnetic resonance and neutron scattering. This program will provide the highest quality interdisciplinary research training to a diverse group of undergraduate students, graduate students and post-doctoral scientists. Students will be trained in cutting edge chemical synthesis and magnetic measurement techniques. The Division of Materials Research and the Division of Chemistry provide support for this project. ****TECHNICAL ABSTRACT**** This award results from a proposal received in response to Nanoscale Science and Engineering initiative, NSF 04-043, category NIRT. It supports an interdisciplinary research effort that will investigate the quantum spin dynamics of nanometer-sized single-molecule magnets (SMMs) using a bottom-up or molecule-based approach. This is a powerful approach in which magnetic nanostructures are synthesized chemically using solution methods. An understanding of the dynamics of nanomagnets is important to technological applications. Of particular interest, and very poorly understood at present, is how the coupling between spins and their environment affect their dynamics. In classical magnetism this coupling leads to dissipation and damping of the magnetization precession. In the quantum case, interaction with the environment limits the spin coherence time and leads to the loss of quantum information. This research program will study: quantum magnetization dynamics; energy and angular momentum relaxation; and spin-excitations in nanomagnets. An important aim is to further understand the microscopic mechanisms of dissipation and decoherence in nanomagnets, and to develop synthetic strategies to mitigate certain environmental effects, such as decoherence. The following experimental techniques will be employed, pulsed EPR, time-resolved and high-sensitivity magnetometry, NMR and inelastic neutron scattering. The latter technique is available to this team through a partnership with Oak Ridge National Lab (ORNL). This program will provide the highest quality interdisciplinary research training to a diverse group of undergraduate, graduate and post-doctoral scientists, which will include training in new chemical synthesis methods and advanced magnetic measurement techniques. The Division of Materials Research and the Division of Chemistry provide support for this project.