Extended ToC

Introduction (slides)

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

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

• 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
• 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

II Mott-Hubbard theory (slides)

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.")

• 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

III Exchange Interactions (slides)

• Kinetic exchange
• Goodenough-Kanamori-Anderson rules
• Inelastic neutron scattering
• Link: Thermal 3-axis spectrameters @ ILL Grenoble
• Kugel-Khomskii exchange, orbital order
• Double exchange
• Colossal magnetoresistance (CMR)

IV Low-dimensional and frustrated materials (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)
• 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