Extended ToC

Introduction (slides)

• Formal and organisational stuff
• What to expect from the lecture
• "Order vs. disorder in a quantum world"

I Atoms in crystalline environment (slides)

• Magnetism of free atoms: Dia- and paramagnetism, Hund's rules
• Crystal fields: breaking SO(3)
• Symmetry, group theory and the Hamiltonian
• Link: Images representing atomic orbitals
• Link: Character tables and symmetry reduction tool
• Link: R.C. Powell: Symmetry, Group Theory, and the Physical Properties of Crystals: via HEIDI)
• Splitting of 3d-levels in the CF
• High-spin/low-spin configurations
• Quenching of the orbital momentum
• Effect of spin-orbit coupling
• Spin Hamiltonian, g-factor
• Jahn-Teller effect
• Link: H. A. Jahn, E. Teller, Original Work: p. 220 of the Proceedings of the Royal Soc. 161
• Orbital order
• Resonant X-ray scattering
• Link: Resonant Inelastic X-Ray Scattering  at ESRF Grenable
• Link: Orbital order in La7/8Sr1/8MnO3

II Molecular magnets: Warm-up with 0D quantum magnets (slides)

Ressources:

• General: Link: MolMag web - a link to molecular magnetism
• Comprehensive Literature: Book Molecular Nanomagnetism by Gatteschi, Sessoli, Villain (link via HEIDI unfortunately expired)
• Textbook: Lanthanide Molecular Magnets (Springer via HEIDI)
• Online resouces: Tutorial on Molecular Magnetis on the MolMagWeb
• Review by Nicholas F. Chilton, Molecular Magnetism Annual Review of Materials Research, Vol. 52:79-101 (with a focus on q-bits)
• Review by Eugenio Coronado, Molecular magnetism: from chemical design to spin control in molecules, materials and devices, Nature Reviews Materials volume 5, pages 87–104 (2020) (a more chemistry perspective)
• Review by Stephen J. Blundell, Molecular magnets, Contemporary Physics 48 (2007) 275-290

Lecture content:

• What is a molecular magnet?
• Spin Hamiltonian, uniaxial and in-plane anisotropy
• Slow relaxation
• Quantum Tunnelling of the Magnetization
• Avouided level crossing, Landau Zener Tunnerling
• Ni2, Mn12, Fe8, Mn4, Mn2Ni3
• micro-Hall and micro-SQUID magnetometry
• ESR on molecular magnets
• Spin crossover materials
• Molecular Q-Bits, spin coherence, dephasing
• Switching magnets: LIESST effect

III Mott-Hubbard physics: Introducing electronic correlation (slides)

Ressources:

• Advanced reading: M. Imada, A. Fujimori, Y. Tokura: Metal-Insulator transitions, Rev. Mod. Phys. 70, 1039–1263 (1998)
• Advanced reading: Tremel et al, Metall oder Nichtmetall? (in German) 1st sentence: "Festkörperphysik ist viel zu spannend, um sie allein den Physikern zu überlassen.")
• P. Fazekas: LECTURE NOTES ON ELECTRON CORRELATION AND MAGNETISM. Very good theory book bridging back magnetism to electron correlations. High level (but also good for experimentalists).
• Daniel I. Khomskii: Basic Aspects of the Quantum Theory of Solids: Order and Elementary Excitations
• D. I. Khomskii, Transition metal compounds, online via HEIDI

Lecture content:

• Reminder: uncorrelated electron systems
• What are electronic correlations?
• Mott transition: general idea
• Phase diagram of V2O3 under pressure
• One-band Hubbard model
• Which electrons are we talking about?
• Hubbard subbands
• Bandwidth-controlled metal-insulator transition
• The example of RNiO3
• Magnetism in the Hubbard model
• PES on Ni, NiO; Cluster approach
• How does a synchrostron work?
• Mott-Hubbard vs. charge transfer insulators
• Charge motion vs. AFM order; stripe formation
• Spin-charge separation

IV 1D and 2D quantum magnets (slides)

• Non-interacting dimers
• RVB state
• Mermin-Wagner theorem
• For experts: Theory tutorial by H. Wagner, U. Schollwoeck on the MW theorem (Link to scholarpedia)
• Educational review on spin liquids (in German): Das Wechselspiel magnetischer Anregungen in Spinflüssigkeiten (Uhrig, Grüninger) Link via Physik Journal DPG
• Uniform AFM 1D Heisenberg chain
• Inelastic Neutron Scattering
• 1D heat transport
• S=1 Haldane chain
• Link: Haldane, PRL 1983 (Link to PRL)
• Link: Haldane's Nobel Prize (particularly p. 15ff)
• Excursus to frustrated 3D magnets: Magnetic monopoles in spin ice
• Further reading: Pauling 1935: The structure and entropy of ice... (Link to JACS)
• Further reading: Gingras 2009: Observing Monopoles in a Magnetic Analog of Ice (Link to Science journal webpages)
• Further reading: Review, Science 2001 (Link to the "Science" journal webpages)
• 2D triangular lattice
• RVB state in 2D
• 2D triangular Ising model
• Topological defects
• Link: Nobel Prize 2016 Haldane, Kosterlitz, Thouless: Scientific background: Topological phase transitions and topological phases of matter
• Link: A new paradigm to distinguish materials according to their topological band nature
• Real space skyrmion soccer: arxiv

V Magnetism in metals and magnetoresistive effects (slides)

• Pauli susceptibility and T-corrections
• Band magnetism, Stoner model
• Stoner enhancement of the susceptibility
• Link: Biography E.C. Stoner/U Leeds
• Circular magnetic x-ray dichroism XMCD
• XMCD introduction: MPG
• Localized magnetic moments in metals
• Kondo effect
• Kondo screening vs RKKY
• RKKY interaction
• Friedel oscillations

VI Magnetoresistive effects (slides)

• Positive MR in metals
• Negative MR in magnetic metals
• Anisotropic MR
• Giant Magnetoresistance (GMR)
• Link Nobel Prize Fert, Grünberg, Royal Swedish Acad. Sc.
• Link: Explanation of GMR@Nobelprize.org
• Tunneling MR (TMR)
• Magnetic data storage, read/write heads

VII. Micro- and Nanomagnets (slides)

• Magnetic domain: stray field, anisotropy
• Single domain magnets
• Superparamagnetism
• MEG; SQUID-based dignostics
• Magnetic hyperthermia
• "Nanomedicine"
• Link: Commercial nanomagnet-based anti-cancer therapy
• Link: Magnetic hyperthermia @ KIP

IV Kondo effect, Heavy fermion systems (slides)

• Localized magnetic moments in metals
• Kondo effect
• Link: Jun Kondo's homepage
• Kondo resonance
• Heavy fermion systems
• Kondo vs. RKKY
• Doniach diagram
• Mixed valence systems
• Kondo insulators
• Advanced reading: P. Coleman, Review 2007