Year: 2022
Type: article
Abstract: Electrons' multiple quantum degrees of freedom can lead to rich physics, including a competition between various exotic ground states, as well as novel applications such as spintronics and valleytronics. Here we report magnetotransport experiments demonstrating how the valley degree of freedom impacts the fractional quantum states (FQHSs), and the related magnetic-flux-electron composite fermions (CFs), at very high magnetic fields in the extreme quantum limit when only the lowest Landau level is occupied. Unlike in other multivalley two-dimensional electron systems such as Si or monolayer graphene and transition-metal dichalcogenides, in our AlAs sample we can continuously tune the valley polarization via the application of in situ strain. We find that the FQHSs remain exceptionally strong even as they make valley polarization transitions, revealing a surprisingly robust ferromagnetism of the FQHSs and the underlying CFs. Our observation implies that the CFs are strongly interacting in our system. We are also able to obtain a phase diagram for the FQHS and CF valley polarization in the extreme quantum limit as we monitor transitions of the FHQSs with different valley polarizations.
Authors: Md. Shafayat Hossain, Meng K. Ma, Y. J. Chung, S. K. Singh, A. Gupta, K. W. West, K. W. Baldwin, L. N. Pfeiffer, R. Winkler, M. Shayegan
Institutions: Princeton University, Northern Illinois University
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: Probing Exotic Phases of Ultra High Mobility Two-Dimensional Electrons, G1138554163, National High Magnetic Field Laboratory Renewal 2018-2022, Supplying the Quantum Materials Community with Record-Mobility Gallium Arsenide Quantum Wells, G354028113, G3560959519, G410635398, Quantum Materials Workshops and Scientist Exchange Program, Electronic spin and valley degrees of freedom - based novel quantum devices, G6010147111, MAGNETO-TRANSPORT IN GAAS TWO-DIMENSIONAL HOLE SYSTEMS
OpenAlex ID: W4309580717