Search for composite fermions at filling factor 5/2: Role of Landau level and subband index

Article

关键词: LATERAL SURFACE SUPERLATTICES;    PAIRED HALL STATE;    QUANTUM HALL;    MAGNETIC-FIELD;    DENSITY MODULATION;    ELECTRON-SYSTEM;    ACOUSTIC-WAVES;    MAGNETORESISTANCE;    TRANSITION;    POTENTIALS;   

DOI  :  10.1103/PhysRevB.95.165438

来源: SCIE

【 摘 要 】

The pairing of composite fermions (CFs), i.e., electron-flux quasiparticles, is commonly proposed to explain the even-denominator fractional quantum Hall state observed at. = 5/2 in the first excited (N = 1) Landau level (LL) of a two-dimensional electron system (2DES). While well established to exist in the lowest (N = 0) LL, much is unknown about CFs in the N = 1 LL. Here we carry out geometric resonance measurements to detect CFs at. = 5/2 by subjecting the 2DES to a one-dimensional density modulation. Our data, taken at a temperature of 0.3 K, reveal no geometric resonances for CFs in the N = 1 LL. In stark contrast, we observe clear signatures of such resonances when. = 5/2 is placed in the N = 0 LL of the antisymmetric subband by varying the 2DES width. This finding implies that the CFs' mean free path is significantly smaller in the N = 1 LL compared to the N = 0 LL. Our additional data as a function of in-plane magnetic field highlight the role of subband index and establish that CFs at. = 5/2 in the N = 0 LL are more anisotropic in the symmetric subband than in the antisymmetric subband.

【 授权许可】

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