Seminar – Jason T. Haraldson – University of North Florida

Examining multi-band effects on the electronic compressibility of a 2D electron gas: Insights into the negative compressibility of LAO/STO

In this study, we investigate the consequences of two electronic bands at the negative electronic compressibility (NEC) cross-over point for a two-dimensional electron gas (2DEG) using a simple homogeneous model with Coulombic interactions and first-order multi-band coupling. We examine the role of effective mass and relative permittivity in relation to the critical carrier density at the cross-over point through a comparison of one- and two-band models. In general, it is shown that the population of a second band, along with the presence of inter-band coupling, can dramatically change the cross-over carrier density. Given the difficulty in determining and confirming multi-band electronic systems, this model provides a potential method for identifying multi-band electronic systems using precise bulk electronic properties measurements. To help illustrate this method, we apply our results to the observed NEC in the 2D electron gas at the interface of LaAlO3/SrTiO3 (LAO/STO) and determine that, for the known parameters of LAO/STO, the system is likely a realization of a two-band 2D electron gas. Furthermore, we provide general limits on the inter-band coupling with respect to the electronic band population.

• Zoom Link: https://kth-se.zoom.us/j/67773156040
• Zoom ID: 627 5910 9592
  
• Date: Wednesday, Feb 03
  
• Time: 5pm Stockholm time