R. G. Herb Condensed Matter Seminars |
Events During the Week of February 15th through February 22nd, 2015
Monday, February 16th, 2015
- Faculty Candidate Seminar
- Custom low-dimensional material systems explored from atom to bulk
- Time: 5:00 pm - 6:00 pm
- Place: 5280 Chamberlin
- Speaker: Adina Luican-Mayer, Argonne National Lab, Center for Nanoscale Materials
- Abstract: The ability to controllably layer atomically thin crystals into custom-made materials holds promise for realizing physical systems with distinct properties, previously inaccessible. The experimental results described in this talk seek to uncover the unique nature of the charge carriers in such few-atoms-thick materials as well as effects that interlayer coupling and disorder have on their properties. Firstly, I will discuss scanning tunneling microscopy (STM) and spectroscopy (STS) experiments performed on graphene systems at low temperatures and in magnetic field. These techniques give access, down to atomic scales, to structural information as well as to the density of states. We find that twisting graphene layers away from the equilibrium Bernal stacking leads to the formation of Moiré patterns and results in a system with novel electronic properties tuned by the twist angle. Moreover, we study Landau quantization in graphene and its dependence on charge carrier density. Performing spatially resolved STM/STS we demonstrate the true discrete quantum mechanical electronic spectrum within the Landau level band near an impurity in graphene in the quantum Hall regime. Secondly, I will discuss temperature-dependent Raman spectroscopy measurements that demonstrate how the number of layers in a crystal of 1T-TaS2 determines the different types of charge density order in this material.
- Host: Coppersmith
Tuesday, February 17th, 2015
- No events scheduled
Wednesday, February 18th, 2015
- Faculty Candidate Seminar
- Spin-charge scattering in Luttinger Liquids
- Time: 4:00 pm
- Place: 4274 Chamberlin Hall
- Speaker: Alex Levchenko
- Abstract: I will discuss the violation of spin-charge separation in generic Luttinger liquids and investigate its effect on the relaxation, thermal and electrical transport of genuine spin-1/2 electron liquids in ballistic quantum wires. We will identify basic scattering processes compatible with the symmetry of the problem and conservation laws that lead to the decay of plasmons into the spin modes and also discuss Brownian backscattering of spin excitations. I will present a closed set of coupled kinetic equations for the spin-charge excitations and solve the problem of electrical and thermal conductance of interacting electrons for an arbitrary relation between the quantum wire length and spin-charge thermalization length.
- Host: Coppersmith
Thursday, February 19th, 2015
- No events scheduled
Friday, February 20th, 2015
- No events scheduled