Molecular Nanomagnets

Name: Molecular Nanomagnets
Brand: Oxford University Press
Price: 83.29 EUR
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VILLAIN DANTE GATTE(Autor*in)

Oxford University Press

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Erschienen am 14. April 2011

408 Seiten

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978-0-19-152436-3 (ISBN)

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Inhalt

Intro
Contents
1 Introduction
2 Magnetic interactions in molecular systems
2.1 The spin Hamiltonian approach
2.1.1 Zeeman and crystal field terms for isolated ions
2.1.2 Electron nucleus (hyperfine) interaction terms
2.1.3 Spin Hamiltonian for pairs
2.2 Single ion levels
2.3 Exchange interaction
2.3.1 Delocalization effects
2.3.2 Spin polarization effects
2.3.3 Some examples
2.3.4 Double exchange
2.3.5 Towards quantitative calculations of exchange interactions
2.4 Through-space and other interactions
2.5 From pairs to clusters and beyond
2.5.1 Isotropic coupling
2.5.2 Magnetic anisotropy in clusters
3 Observation of microscopic magnetism
3.1 Magnetic techniques
3.1.1 Standard magnetometry
3.1.2 Time-dependent measurements
3.1.3 Micro-SQUID and micro-Hall probe techniques
3.1.4 Torque magnetometry
3.1.5 AC susceptometry
3.2 Specific heat measurements
3.2.1 The specific heat and its magnetic part
3.2.2 Magnetic specific heat at equilibrium
3.2.3 Measurement of the magnetic specific heat: the relaxation method
3.2.4 Magnetic specific heat in an alternating current
3.3 Magnetic resonances
3.3.1 Electron paramagnetic resonance
3.3.2 Nuclear magnetic resonance
3.3.3 Muon spin resonance (µSR)
3.4 Neutron techniques
3.4.1 Polarized neutron diffraction
3.4.2 Inelastic neutron scattering
4 Single-molecule magnets
4.1 Serendipity versus rational design of SMMs
4.2 Synthetic strategies to SMMs
4.3 The use of preformed building blocks
4.3.1 Cyanide-based clusters
4.3.2 The disruption of oxocentred carboxylate triangles
4.4 Polyoxometalates
4.4.1 The role of pentagons
4.5 The templating effect
4.6 Solvothermal synthesis
4.7 A survey of the most investigated SMMs
4.7.1 The archetypal Mn[sub(12)] acetate cluster
4.7.2 The Mn[sub(12)] family
4.7.3 The reduced species of Mn[sub(12)] clusters
4.7.4 Fe[sub(8)] clusters
4.7.5 Mn[sub(4)] clusters
5 Thermally activated magnetic relaxation
5.1 Relaxation and relaxation time
5.2 Potential barrier
5.3 Transition probabilities and the master equation
5.4 Solution of the master equation
5.5 Spin-phonon interaction
5.5.1 Basic features
5.5.2 Local rotation
5.5.3 Local strain
5.5.4 Terms linear in the spin operators
5.6 Transition probabilities and the golden rule
5.7 Qualitative formulae
5.8 Multiphonon processes
5.9 Spin-phonon interactions resulting from exchange
5.10 Effect of photons
5.10.1 Phonons and photons
5.10.2 Photons at thermal equilibrium
5.10.3 The beauty of light
5.10.4 Classical electromagnetism and quantum electrodynamics
5.10.5 Coherence and superradiance
5.11 Limitations of the model
6 Magnetic tunnelling of an isolated spin
6.1 Spin tunnelling
6.1.1 Particle tunnelling: a reminder
6.1.2 An example
6.1.3 The case s = 1/2
6.1.4 Case of an arbitrary spin
6.1.5 Delocalization
6.1.6 Large spin = classical spin?
6.1.7 Approximate localized eigenstates
6.2 Symmetry and selection rules for tunnelling
6.3 Tunnelling width for an isolated spin
6.4 Tunnel splitting according to perturbation theory
6.5 Time-dependent wavefunction: magnetic tunnelling
6.6 Effect of a field along the hard axis
6.7 Evaluation of the tunnel splitting for large spins
6.7.1 General methods
6.7.2 Example: the Hamiltonian (2.5)
6.8 Diabolic points
6.8.1 Degeneracy with and without symmetry
6.8.2 The von Neumann-Wigner theorem
6.8.3 The quest of the Devil
7 Introduction to path integrals
7.1 General ideas
7.2 The anharmonic oscillator
7.3 Tunnel effect and instantons
7.4 The path integral method applied to spins
8 Tunnelling in a time-dependent magnetic field at low temperature
8.1 Advantages of a time-dependent magnetic field
8.2 Fast sweeping and adiabatic limit
8.3 Calculation of the reversal probability
8.3.1 Equations of motion
8.3.2 The solution of Landau, Zener, and Stückelberg
8.3.3 Fast sweeping
8.3.4 Sweeping back and forth through the resonances
9 Interaction of a spin with the external world at low temperature
9.1 Coherence, incoherence, and relaxation
9.1.1 Low temperatures
9.1.2 The window mechanism
9.2 Hyperfine interactions
9.2.1 The hyperfine field and its order of magnitude
9.2.2 Experimental evidence of hyperfine interactions
9.2.3 Linewidth of hyperfine origin
9.2.4 Relaxation of hyperfine origin
9.2.5 Effect of hyperfine interactions in the case of time-dependent fields
9.2.6 How do nuclear spins relax?
9.3 Relaxation by dipole interactions between molecular spins
9.4 Other theoretical approches
9.4.1 The theory of Caldeira and Leggett
9.4.2 Hyperfine interactions according to Prokofev and Stamp
9.4.3 Hyperfine interactions as a random walk
9.4.4 Tunnelling as an effect of hyperfine interactions
10 Tunnelling between excited states
10.1 The three relaxation regimes
10.2 Tunnelling at resonance
10.3 Tunnel probability into an excited state
10.4 A remark about the dynamic susceptibility
10.5 Two different types of relaxation
10.6 Effect of a time-dependent field at T ? 0
10.7 Role of excited spin states
10.8 Magnetic specific heat in the presence of spin tunnelling
10.9 Tunnelling out of resonance
11 Coherence and decoherence
11.1 The mystery of Schrödinger's cat
11.2 The density matrix
11.3 Master equation for the density matrix
11.4 Properties of the master matrix ?
11.5 Coherence and muon spectroscopy
11.6 Case of spin tunnelling
11.7 Spin tunnelling between localized states
11.7.1 Decoherence by nuclear spins in zero field
11.8 Potential applications of quantum coherence: quantum computing
12 Disorder and magnetic tunnelling
12.1 Experimental evidence of disorder
12.2 Landau-Zener-Stückelberg experiment with a distribution of tunnel frequencies
12.3 The scaling law of Chudnovsky and Garanin
12.4 Other distortion isomers in Mn[sub(12)]ac
12.5 Spin glass phases?
12.6 Conclusion
13 More experiments on single-molecule magnets
13.1 The advantages of complexity
13.2 Intercluster interactions in Mn[sub(4)] clusters
13.2.1 The effects of intercluster interactions on magnetic tunnelling
13.2.2 The effects of magnetic tunnelling on long-range magnetic order
13.3 Tunnelling and electromagnetic radiation
14 Other Magnetic Molecules
14.1 Magnetic wheels
14.1.1 Iron rings
14.2 Grids
14.3 Three-dimensional clusters
14.3.1 Spherical antiferromagnets
14.3.2 Vanadium cluster
14.3.3 Mixed-valence systems
15 Emerging trends in molecular nanomagnetism
15.1 SMMs based on a single metal ion
15.2 Single chain magnets
A Systems of units, physical constants and basic mathematical tools
A.1 International system of units, electromagnetic CGS and electrostatic CGS systems
A.2 Gauss' system of units
A.3 Other common units
A.4 Physical constants
A.5 Stevens operators
A.6 3j- and 6j-symbols
A.7 Different notation
B The magnetic field
B.1 A complicated vocabulary
B.2 Demagnetizing field and local field
B.3 Free energy
C How irreversibility comes in
D Basic properties of the master equation
E Derivation of the Arrhenius law
F Phonons and how to use them
F.1 Memento of the basic formulae
F.2 Numerical calculation of the relaxation rate
G High-order perturbation theory
H Proof of the Landau-Zener-Stückelberg formula
I Tunnelling between hyperfine states
J Specific heat
J.1 Specific heat at equilibrium and at high frequency
J.2 Frequency-dependent specific heat
K Master equation for the density matrix
K.1 Basic hypotheses
K.2 An expression for the density matrix of a spin system
K.3 Perturbation theory
K.3.1 Diagrammatic expansion
K.3.2 First and second diagrams
K.3.3 Third to sixth diagrams
K.3.4 Summary of this section
K.4 Tunnelling
References
Index
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
V
W
X
Z

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