Aims: Understanding the phenomenon of spin-charge separation. Understanding that quasi-particles in solid are not the known quantities from atomic physics. Eventually you should be able to comment on the following abstract by Mark Schubel:

"Being in Two Places at Once:Spin-Charge Separation: High-energy experiments have shown that the electron is a point-like particle with spin-1/2 and electric charge -e. In highly correlated condensed matter systems these two properties can decouple in the lowest level excitations with the creationof two new quasiparticles: spinons (which carry spin) and chargons (which carry electric charge)."

Material:

• 3 Slides of a lecture by G. Sawatzki to be discussed
• The paper Sawatzki is referring to: Kim2006Nature

Guiding questions:

• What are characteristics of quasiparticles?
• Do you know other QPs in condensed matter physics?
• What is a spinon and a holon?
• Why Sawatky says that spinons live on another lattice than the holons?
• What is the experimental proof that spin-charge separation does exist?
• What determined the velocity of sppinons and holons?
• Why a 1D system is needed?
• Why SrCuO2 can be considered a quasi 1D system (while being a 3-dimensional single crystalline material)?

Helpful textbooks:

• D.I. Khomskii: Basic Aspects of the Quantum Theory of Solids: Order and Elementary Excitations
• D.I. Khomskii: Transition metal compounds (online via heidi): On spinons and holons