TY - JOUR
T1 - Spontaneous Valley Polarization of Itinerant Electrons
AU - Hossain, Md S.
AU - Ma, M. K.
AU - Villegas-Rosales, K. A.
AU - Chung, Y. J.
AU - Pfeiffer, L. N.
AU - West, K. W.
AU - Baldwin, K. W.
AU - Shayegan, M.
N1 - Funding Information:
We acknowledge support through the U.S. Department of Energy Basic Energy Science (Grant No. DEFG02-00-ER45841) for measurements, and the National Science Foundation (Grants No. DMR 2104771, No. DMR 1709076, No. ECCS 1906253, and No. MRSEC DMR 1420541), and the Gordon and Betty Moore Foundations EPiQS Initiative (Grant No. GBMF9615 to L. N. P.) for sample fabrication and characterization. We also thank J. K. Jain, H. D. Drew, S. A. Kivelson, and M. A. Mueed for illuminating discussions.
Publisher Copyright:
© 2021 American Physical Society.
PY - 2021/9/10
Y1 - 2021/9/10
N2 - Memory or transistor devices based on an electron's spin rather than its charge degree of freedom offer certain distinct advantages and comprise a cornerstone of spintronics. Recent years have witnessed the emergence of a new field, valleytronics, which seeks to exploit an electron's valley index rather than its spin. An important component in this quest would be the ability to control the valley index in a convenient fashion. Here we show that the valley polarization can be switched from zero to 1 by a small reduction in density, simply tuned by a gate bias, in a two-dimensional electron system. This phenomenon, which is akin to Bloch spin ferromagnetism, arises fundamentally as a result of electron-electron interaction in an itinerant, dilute electron system. Essentially, the kinetic energy favors an equal distribution of electrons over the available valleys, whereas the interaction between electrons prefers single-valley occupancy below a critical density. The gate-bias-tuned transition we observe is accompanied by a sudden, twofold change in sample resistance, making the phenomenon of interest for potential valleytronic transistor device applications. Our observation constitutes a quintessential demonstration of valleytronics in a very simple experiment.
AB - Memory or transistor devices based on an electron's spin rather than its charge degree of freedom offer certain distinct advantages and comprise a cornerstone of spintronics. Recent years have witnessed the emergence of a new field, valleytronics, which seeks to exploit an electron's valley index rather than its spin. An important component in this quest would be the ability to control the valley index in a convenient fashion. Here we show that the valley polarization can be switched from zero to 1 by a small reduction in density, simply tuned by a gate bias, in a two-dimensional electron system. This phenomenon, which is akin to Bloch spin ferromagnetism, arises fundamentally as a result of electron-electron interaction in an itinerant, dilute electron system. Essentially, the kinetic energy favors an equal distribution of electrons over the available valleys, whereas the interaction between electrons prefers single-valley occupancy below a critical density. The gate-bias-tuned transition we observe is accompanied by a sudden, twofold change in sample resistance, making the phenomenon of interest for potential valleytronic transistor device applications. Our observation constitutes a quintessential demonstration of valleytronics in a very simple experiment.
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U2 - 10.1103/PhysRevLett.127.116601
DO - 10.1103/PhysRevLett.127.116601
M3 - Article
C2 - 34558923
AN - SCOPUS:85114881480
SN - 0031-9007
VL - 127
JO - Physical Review Letters
JF - Physical Review Letters
IS - 11
M1 - 116601
ER -