TY - JOUR
T1 - Geometric resonance of four-flux composite fermions
AU - Hossain, Md Shafayat
AU - Ma, Meng K.
AU - Mueed, M. A.
AU - Kamburov, D.
AU - Pfeiffer, L. N.
AU - West, K. W.
AU - Baldwin, K. W.
AU - Winkler, R.
AU - Shayegan, M.
N1 - Publisher Copyright:
© 2019 American Physical Society.
PY - 2019/7/17
Y1 - 2019/7/17
N2 - Two-dimensional interacting electrons exposed to strong perpendicular magnetic fields generate emergent, exotic quasiparticles phenomenologically distinct from electrons. Specifically, electrons bind with an even number of flux quanta, and transform into composite fermions (CFs). Besides providing an intuitive explanation for the fractional quantum Hall states, CFs also possess Fermi-liquid-like properties, including a well-defined Fermi sea, at and near even-denominator Landau-level filling factors such as ν=1/2 or 1/4. Here, we directly probe the Fermi sea of the rarely studied four-flux CFs near ν=1/4 via geometric resonance experiments. The data reveal some unique characteristics. Unlike in the case of two-flux CFs, the magnetic field positions of the geometric resonance resistance minima for ν<1/4 and ν>1/4 are symmetric with respect to the position of ν=1/4. However, when an in-plane magnetic field is applied, the minima positions become asymmetric, implying a mysterious asymmetry in the CF Fermi sea anisotropy for ν<1/4 and ν>1/4. This asymmetry, which is in stark contrast to the two-flux CFs, suggests that the four-flux CFs on the two sides of ν=1/4 have very different effective masses, possibly because of the proximity of the Wigner crystal formation at small ν.
AB - Two-dimensional interacting electrons exposed to strong perpendicular magnetic fields generate emergent, exotic quasiparticles phenomenologically distinct from electrons. Specifically, electrons bind with an even number of flux quanta, and transform into composite fermions (CFs). Besides providing an intuitive explanation for the fractional quantum Hall states, CFs also possess Fermi-liquid-like properties, including a well-defined Fermi sea, at and near even-denominator Landau-level filling factors such as ν=1/2 or 1/4. Here, we directly probe the Fermi sea of the rarely studied four-flux CFs near ν=1/4 via geometric resonance experiments. The data reveal some unique characteristics. Unlike in the case of two-flux CFs, the magnetic field positions of the geometric resonance resistance minima for ν<1/4 and ν>1/4 are symmetric with respect to the position of ν=1/4. However, when an in-plane magnetic field is applied, the minima positions become asymmetric, implying a mysterious asymmetry in the CF Fermi sea anisotropy for ν<1/4 and ν>1/4. This asymmetry, which is in stark contrast to the two-flux CFs, suggests that the four-flux CFs on the two sides of ν=1/4 have very different effective masses, possibly because of the proximity of the Wigner crystal formation at small ν.
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U2 - 10.1103/PhysRevB.100.041112
DO - 10.1103/PhysRevB.100.041112
M3 - Article
AN - SCOPUS:85070226332
SN - 2469-9950
VL - 100
JO - Physical Review B
JF - Physical Review B
IS - 4
M1 - 041112
ER -