arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2001.06524cond-mat.str-el
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复合费米子的费米面

Fermi surfaces of composite fermions

R. N. Bhatt, Matteo Ippoliti

摘要:

分数量子霍尔效应是近四十年前在垂直磁场作用下的二维电子系统中发现的。它有助于启动领域的拓扑阶段,此外,由于淬火的动能,赋予新的含义短语“相关的问题”。大多数的BH-H相都像绝缘体和超导体一样有间隙;然而,一个小的子集,具有朗道能级的偶数分母分数填充nu,典型的是nu = 1/2,被发现是无间隙的,费米表面类似于金属。我们讨论了我们的结果,数值计算得到的使用无限密度矩阵重整化群(iDMRG)计划,非各向同性畸变的效果与离散N重旋转对称的费米面在零磁场上的费米面的相关nu = 1/2状态。我们发现,虽然N = 2(椭圆形)失真的响应是显着的(并与实验观察,没有可调参数),它下降得非常迅速,N的增加。我们还发现了其他一些反常现象,如费米面断裂成不相交的碎片的弹性,这突出了由动能形成的费米面与由哈密顿量中的纯势能项形成的费米面之间的差异。

英文摘要:

The fractional quantum Hall (FQH) effect was discovered in two-dimensional electron systems subject to a large perpendicular magnetic field nearly four decades ago. It helped launch the field of topological phases, and in addition, because of the quenching of the kinetic energy, gave new meaning to the phrase "correlated matter". Most FQH phases are gapped like insulators and superconductors; however, a small subset with even denominator fractional fillings nu of the Landau level, typified by nu = 1/2, are found to be gapless, with a Fermi surface akin to metals. We discuss our results, obtained numerically using the infinite Density Matrix Renormalization Group (iDMRG) scheme, on the effect of non-isotropic distortions with discrete N-fold rotational symmetry of the Fermi surface at zero magnetic field on the Fermi surface of the correlated nu = 1/2 state. We find that while the response for N = 2 (elliptical) distortions is significant (and in agreement with experimental observations with no adjustable parameters), it decreases very rapidly as N is increased. Other anomalies, like resilience to breaking the Fermi surface into disjoint pieces, are also found. This highlights the difference between Fermi surfaces formed from the kinetic energy, and those formed of purely potential energy terms in the Hamiltonian.

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