R. G. Herb Condensed Matter Seminars |
Events During the Week of February 12th through February 19th, 2023
Monday, February 13th, 2023
- No events scheduled
Tuesday, February 14th, 2023
- Discovering and Engineering Two-Dimensional Magnetism and Superconductivity
- Time: 10:00 am - 6:00 pm
- Place: 5310 Chamberlin
- Speaker: Tiancheng Song, Princeton
- Abstract: Understanding and manipulating macroscopic quantum phenomena such as superconductivity and magnetism are crucial for future quantum science and technology. Two-dimensional (2D) materials and their van der Waals (vdW) heterostructures offer a promising platform to achieve this goal due to their exceptionally broad tunability. In this talk, I will highlight the potential of such a platform through two outstanding examples: 2D magnetism and 2D superconductivity. In the first part, I will talk about a series of emergent phenomena enabled by the vdW nature of 2D magnets, including (1) giant tunneling magnetoresistance enhanced by spin-filtering effects; (2) control of interlayer magnetism by tuning layer stacking; (3) novel moiré magnetism by twisting two layers of 2D magnets. In the second part, I will introduce a new probe to detect superconducting fluctuations down to millikelvin temperatures based on thermoelectric measurements of a monolayer nanoflake. I will discuss surprisingly unusual vortex Nernst signals, which reveal an unconventional superconducting quantum criticality in an electrically tunable 2D superconductor. Finally, I will conclude by highlighting unique opportunities for discovering and engineering new quantum materials and electronic phases in two dimensions.
- Host: Victor Brar
Wednesday, February 15th, 2023
- No events scheduled
Thursday, February 16th, 2023
- Strange Metal Behavior in the Hall Coefficient of BaFe2(As,P)2
- Time: 10:00 am - 6:00 pm
- Place: 5310 Chamberlin
- Speaker: Ian Hayes, University of Maryland
- Abstract: Even after decades of research on the high-Tc cuprates, several parts of their phase diagrams remain mysterious, especially the normal state above Tc near optimal doping, a region commonly referred to as the strange metal phase. New avenues for studying this physics were opened up by the discovery of the iron-based high-Tc materials, which also exhibit strange metal characteristics, particularly a T-linear resistivity and a roughly 1/T Hall coefficient near optimal doping. In this talk I will present measurements of the Hall coefficient in phosphorous-doped BaFe2As2 in fields of up to 65 tesla, which is enough to suppress superconductivity even at optimal doping. These measurements reveal a striking parallel between the effects of increasing magnetic field and the effects of increasing temperature, a phenomenon that is reminiscent of the field-temperature scaling seen in the resistivity of this compound. This characteristic field dependence allows us to clearly identify the extent of strange metal physics in the entire phosphorous-doping phase diagram. Intriguingly, the presence of strange metal behavior in the Hall coefficient is directly related to the presence of the superconductivity across the phase diagram. I will discuss the implications of these observations for different approaches to the strange metal as well as the opportunities they present for future research.
- Host: Victor Brar
Friday, February 17th, 2023
- No events scheduled