Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session A04: Quantum Hall States at Even-Denominator Filling
8:00 AM–11:00 AM,
Monday, March 5, 2018
LACC Room: 151
Sponsoring Unit: DCMP
Chair: Ravindra Bhatt, Princeton University
Abstract: A04.00001 : Effect of band anisotropy on the Fermi contour of composite fermions at half filling*
8:00 AM–8:36 AM
View Presentation Abstract
(Physics, Princeton Univ)
(Physics, Princeton Univ)
Fractional quantum Hall states possess a geometric degree of freedom arising from the competition between the geometry of the band structure and that of Coulomb interactions, which in general can be different. In the composite Fermi liquid (CFL) state at filling nu=½, this degree of freedom determines the shape of the Fermi sea of composite fermions (CFs).
We study [1-3] the transference of the shape of the Fermi surface from the zero-field carriers to the high-field CFs by performing numerical simulations of the CFL state using an infinite-cylinder density matrix renormalization group (DMRG) method . We consider a variety of anisotropic single-particle band structures, including elliptical (band mass) anisotropy  as well as higher-order rotational anisotropy (e.g. with square symmetry) . In each case, we map the shape of the CF Fermi sea, quantify its anisotropy αCF (defined as the ratio of the longest and shortest Fermi wavevectors), and compare it to that of the zero-field fermions, αF. We complement our numerical study with an analysis based on anisotropic pseudopotentials . Our results correctly predict, without adjustable parameters, the results of experiments on GaAs quantum wells subjected to strain , where, for Coulomb interactions, the elliptical anisotropy parameters for zero-field fermions and high-field CFs are found to obey αCF = αF½. Moreover, they confirm that distortions with higher-order rotational symmetry have a small (though generally non-zero) effect on the CFs.
This work was done in collaboration with S. D. Geraedts and R. N. Bhatt (Dept. of Electrical Engineering, Princeton University).
 M. Ippoliti, S. D. Geraedts and R. N. Bhatt, PRB 95, 201104(R) (2017)
 Same authors, PRB 96, 045145 (2017)
 Same authors, PRB 96, 115151 (2017)
 M. P. Zaletel et al., PRB 91, 045115 (2015)
 B. Yang et al., PRL 118, 146403 (2017)
 I. Jo et al., PRL 119, 016402 (2017)
*This work was supported by Department of Energy BES Grant DE-SC0002140
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