[Dec. 8] Physics Special Seminar - Dr. Yoon-Jang Chung (UMD)

물리학과 특별세미나 개최 안내

물리학과에서는 특별세미나를 아래와 같이 개최하오니 관심있는 분들의 많은 참석을 바랍니다.

1. 연사: 정윤장 박사 (UMD)

2. 일시: 2022. 12. 8(목), 오후 4시
3. 장소: 공학3동 302호 (세미나실)

4. 제목: Ultra-high-quality quantum materials

Quantum materials can loosely be defined as those used for the investigation of quantum phenomena such as entanglement, many-body physics, or topological behavior. While the physical properties of the materials themselves obviously play an essential role in determining whether a material can be classified as a quantum material or not, oftentimes what is equally important is the quality of the material. This is because typically, quantum phenomena are inherently delicate and hence quite susceptible to any perturbative species within the system that could cause a scattering event.

A hallmark example that demonstrates the impact of material quality on quantum science is the two-dimensional electron system (2DES) hosted in GaAs/AlAs based quantum wells.

Over the past few decades, a plethora of quantum phases such as Wigner solids, odd- and even denominator fractional quantum Hall states (FQHSs), and stripe/nematic phases have materialized in these 2DESs as sample quality progressed. In this talk, I will discuss how to fabricate ultra-high-quality AlAs and GaAs 2DESs via molecular beam epitaxy. The samples presented in this work have the highest reported electron mobility in their corresponding systems, with the GaAs 2DESs going a step further and holding the world record for electron mobility in any system ever measured by mankind. Such levels of sample cleanliness have an immediate impact on the study of quantum many-body physics, as demonstrated by the emergence of several new interaction-driven phases. While GaAs and AlAs are discussed as examples here, similar design and growth principles can be applied to other group IV, III-V, and II-VI material systems to expand the list of ultra-high-quality quantum materials.