Author: Andreas SieberPublisher:
ISBN:
Category :
Languages : en
Pages : 129
Book Description
Inelastic Neutron Scattering Studies on Spin Clusters and Single-molecule Magnets
Author: Andreas SieberStudies of Single-molecule Magnets and Spin Clusters by Inelastic Neutron Scattering and Magnetic Measurements
Author: Roland BircherInelastic Neutron Scattering of Spin Clusters
Author: Hanspeter AndresNeutron Scattering Investigations of Zero- and One-dimensional Quantum Magnets
Author: Oliver PieperPublisher:
ISBN: 9783832527303
Category :
Languages : en
Pages : 270
Book Description
This thesis deals with the investigation of two different types of low-dimensional quantum magnets using the technique of neutron scattering.In the first part, the magnetic properties of three Mn_6-based single molecule magnets are explored by means of inelastic neutron scattering. The experimental data reveal that small structural distortions of the molecular geometry produce a significant effect on the energy level diagram and therefore on the magnetic properties of the molecules. It will be shown that the giant spin model completely fails to describe the spin level structure of the ground spin multiplets and that the excited S-multiplets play a key role in determining the effective energy barrier for the magnetization reversal.The second part of this thesis presents an in-depth study of the nuclear and magnetic properties of the quasi-one-dimensional Heisenberg antiferromagnet CaV_2O_4. The magnetism in this system arises from the partially filled t_{2g-levels of the V^{3+-ions, which in addition give an orbital degree of freedom to the system.Single crystal and powder neutron diffraction as well as neutron spectroscopy are used to determine the nuclear and magnetic structure as well as the complex excitation spectrum of CaV_2O_4. The results are analysed theoretically and from this the leading exchange paths are deduced and discussed in terms of orbital ordering.
Molecular Cluster Magnets
Author: Richard WinpennyPublisher: World Scientific
ISBN: 9814322954
Category : Science
Languages : en
Pages : 312
Book Description
This work covers new developments in the field of molecular nanomagnetism, complementing previous books in this area (for example the volume by Gatteschi, Sessoli and Villain on Single Molecule Magnets). The book is written by experts in the field and is intended as a compilation of critical reviews of new areas rather than a comprehensive text.
Some neutron scattering studies on magnetic and molecular phase...
Author: Leendert BevaartProbing Magnetic and Vibrational Properties of Molecular Compounds by Neutron Scattering
Author: Shelby Elizabeth StavretisPublisher:
ISBN:
Category : Molecular spectroscopy
Languages : en
Pages : 292
Book Description
The primary focus of this dissertation is using inelastic neutron scattering (INS) to probe magnetic excitations in paramagnetic complexes including single-molecule magnets (SMMs). Other related studies include the following: (1) Simulating vibrational frequencies to understand spin-phonon coupling (SPC) in a single-molecule magnet; (2) Using quasi-elastic neutron scattering (QENS) to study molecular dynamics of a paramagnet. Zero-field splitting (ZFS) parameters (axial: D and rhombic: E) of metalloporphryins Fe(TPP)X [X = F, Br, I; H2TPP = tetraphenylporphyrin] have been directly determined by INS. These studies provide a complete determination of ZFS parameters for a metalloporphryin halide series demonstrating that D increases from F to I complexes. Ab initio methods were led to the understanding of the origin of the halide trend. INS has also been used to probe several Co(II) and an Er(III) SMMs. The magnetic excitations were determined by a variety of methods demonstrating that INS is a unique technique to determine the magnitude of these excitations. Most prominently, INS conducted under variable magnetic fields, reveals magnetic excitations in single crystals and powder samples in the energy region above 40 cm-1. In addition, this work shows a unique strength of INS to show the origin of spin-phonon entangled peaks at 0 T. Vibrational frequencies and simulation of atomic displacements in Co(II) SMMs have been calculated via ab intio methods to study SPC. Raman spectroscopy of Co(acac)2(H2O)2 (acac = acetylacetonate), Co(acac)2(D2O)2 and Co(acac-d7)2(D2O)2 gives experimental SPC constants of different magnitudes. By probing the displacements in atoms in the SMMs, a correlation between the largest bond angle change in the first coordination sphere and largest SPC constant has been discovered. This work leads to understanding of how the electron spins in the Co(II) complexes interact with phonons in the energy region near the magnetic excitation. QENS has been used to study methyl rotation in Co(acac)2(D2O)2, which behaves as a paramagnet in the temperature range probed (80–100 K). The use of external magnetic fields leads to the observation of field-dependent methyl rotation. This field-dependent behavior sheds light on intermolecular interactions in the solid state.
Molecular Cluster Magnets
Author: Richard WinpennyPublisher: World Scientific
ISBN: 9814322946
Category : Science
Languages : en
Pages : 312
Book Description
This work covers new developments in the field of molecular nanomagnetism, complementing previous books in this area (for example the volume by Gatteschi, Sessoli and Villain on Single Molecule Magnets). The book is written by experts in the field and is intended as a compilation of critical reviews of new areas rather than a comprehensive text.
Neutron Scattering - Magnetic and Quantum Phenomena
Author: Publisher: Elsevier
ISBN: 0128020938
Category : Science
Languages : en
Pages : 534
Book Description
Neutron Scattering - Magnetic and Quantum Phenomena provides detailed coverage of the application of neutron scattering in condensed matter research. The book's primary aim is to enable researchers in a particular area to identify the aspects of their work where neutron scattering techniques might contribute, conceive the important experiments to be done, assess what is required to carry them out, write a successful proposal for one of the major user facilities, and perform the experiments under the guidance of the appropriate instrument scientist. An earlier series edited by Kurt Sköld and David L. Price, and published in the 1980s by Academic Press as three volumes in the series Methods of Experimental Physics, was very successful and remained the standard reference in the field for several years. This present work has similar goals, taking into account the advances in experimental techniques over the past quarter-century, for example, neutron reflectivity and spin-echo spectroscopy, and techniques for probing the dynamics of complex materials of technological relevance. This volume complements Price and Fernandez-Alonso (Eds.), Neutron Scattering - Fundamentals published in November 2013. Covers the application of neutron scattering techniques in the study of quantum and magnetic phenomena, including superconductivity, multiferroics, and nanomagnetism Presents up-to-date reviews of recent results, aimed at enabling the reader to identify new opportunities and plan neutron scattering experiments in their own field Provides a good balance between theory and experimental techniques Provides a complement to Price and Fernandez-Alonso (Eds.), Neutron Scattering - Fundamentals published in November 2013
Elements of Slow-Neutron Scattering
Author: J. M. CarpenterPublisher: Cambridge University Press
ISBN: 0521857813
Category : Science
Languages : en
Pages : 539
Book Description
This book provides a comprehensive and up-to-date introduction to the fundamental theory and applications of slow-neutron scattering.