PhD Defense: Electron-phonon coupling in the time domain: TR-ARPES studies by a cavity-based XUV laser

Event Date:
2022-04-28T10:00:00
2022-04-28T12:00:00
Event Location:
zoom : https://ubc.zoom.us/j/63707269353?pwd=YnZKMzd4K0NKWGtESUJSS2JXNGU5Zz09 Passcode: 486279
Speaker:
MengXing Na, PhD student
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Intended Audience:
Public
Event Information:

Quantum materials manifest exciting macroscopic electronic properties that emerge from microscopic electron interactions -- such as those between the electron and the lattice. Extensive research effort has been dedicated to understanding the physics of these materials; among these, angle-resolved photoemission spectroscopy (ARPES) has the unique capability of taking ``photos" of the electronic band structure. This band structure is a fingerprint of the electronic properties of each material and encodes microscopic electron interactions. By combining ARPES with an ultrafast laser source, we can turn “photos" of the electronic band structure into “movies" and study how electrons respond to external perturbation, such as a short pulse of light. This technique is called time-resolved ARPES (TR-ARPES).

 

 In particular, the interaction between electrons and the lattice is responsible for a host of quantum phenomena, including the well-known superconductivity. In this thesis, we study graphite using a new extreme ultraviolet laser. We observe that electrons in graphite preferentially interact with a specific mode of lattice vibration. From the electron dynamics, we quantitatively extract the interaction strength between the electrons and this lattice vibration with a simple, transparent model and find that it agrees well with first-principles calculations. With this demonstration, we show that the maturation of laser technology has significantly advanced the capabilities of TR-ARPES, which readily serves to further our understanding of quantum materials.

Add to Calendar 2022-04-28T10:00:00 2022-04-28T12:00:00 PhD Defense: Electron-phonon coupling in the time domain: TR-ARPES studies by a cavity-based XUV laser Event Information: Quantum materials manifest exciting macroscopic electronic properties that emerge from microscopic electron interactions -- such as those between the electron and the lattice. Extensive research effort has been dedicated to understanding the physics of these materials; among these, angle-resolved photoemission spectroscopy (ARPES) has the unique capability of taking ``photos" of the electronic band structure. This band structure is a fingerprint of the electronic properties of each material and encodes microscopic electron interactions. By combining ARPES with an ultrafast laser source, we can turn “photos" of the electronic band structure into “movies" and study how electrons respond to external perturbation, such as a short pulse of light. This technique is called time-resolved ARPES (TR-ARPES).    In particular, the interaction between electrons and the lattice is responsible for a host of quantum phenomena, including the well-known superconductivity. In this thesis, we study graphite using a new extreme ultraviolet laser. We observe that electrons in graphite preferentially interact with a specific mode of lattice vibration. From the electron dynamics, we quantitatively extract the interaction strength between the electrons and this lattice vibration with a simple, transparent model and find that it agrees well with first-principles calculations. With this demonstration, we show that the maturation of laser technology has significantly advanced the capabilities of TR-ARPES, which readily serves to further our understanding of quantum materials. Event Location: zoom : https://ubc.zoom.us/j/63707269353?pwd=YnZKMzd4K0NKWGtESUJSS2JXNGU5Zz09 Passcode: 486279