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arXiv 2007.10208cond-mat.str-el
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强关联费米子系统Luttinger定理和粒子-空穴对称性的精确实验检验

Precise Experimental Test of the Luttinger Theorem and Particle-Hole Symmetry for a Strongly Correlated Fermionic System

Md. S. Hossain, M. A. Mueed, M. K. Ma, K. A. V. Rosales, Y. J. Chung, L. N. Pfeiffer, K. W. West, K. W. Baldwin, M. Shayegan

摘要:

物理学中的一个基本概念是费米面,即在绝对零度下包含所有占据的量子态的动量空间中的恒定能量面。在1960年,Luttinger假设费米面所包围的区域应该保持不受影响,即使当电子-电子相互作用开启时,只要相互作用不引起相变。在强相互作用系统(如高$T_{c}$超导体)中,理解费米面大小的决定因素是一个关键而尚未解决的问题。在这里,我们提出了一个精确的测试Luttinger定理的二维费米液体系统中的奇异准粒子本身出现的强相互作用,即费米海的复合费米子(CF)。通过直接的,几何共振测量的CFs的费米波矢量下降到非常低的电子密度,我们表明,Luttinger定理是服从一个显着的相互作用强度范围内,在这个意义上说,费米海面积是由密度的\textit{minority carriers}在最低的朗道水平。我们的数据也解决了目前正在进行的争论是否CF遵守粒子-空穴对称性,如果他们是狄拉克粒子。我们发现,遵守粒子-空穴对称性,但测量的费米海面积从狄拉克模型预测的CFs的定量不同。

英文摘要:

A fundamental concept in physics is the Fermi surface, the constant-energy surface in momentum space encompassing all the occupied quantum states at absolute zero temperature. In 1960, Luttinger postulated that the area enclosed by the Fermi surface should remain unaffected even when electron-electron interaction is turned on, so long as the interaction does not cause a phase transition. Understanding what determines the Fermi surface size is a crucial and yet unsolved problem in strongly interacting systems such as high-$T_{c}$ superconductors. Here we present a precise test of the Luttinger theorem for a two-dimensional Fermi liquid system where the exotic quasi-particles themselves emerge from the strong interaction, namely for the Fermi sea of composite fermions (CFs). Via direct, geometric resonance measurements of the CFs' Fermi wavevector down to very low electron densities, we show that the Luttinger theorem is obeyed over a significant range of interaction strengths, in the sense that the Fermi sea area is determined by the density of the \textit{minority carriers} in the lowest Landau level. Our data also address the ongoing debates on whether or not CFs obey particle-hole symmetry, and if they are Dirac particles. We find that particle-hole symmetry is obeyed, but the measured Fermi sea area differs quantitatively from that predicted by the Dirac model for CFs.

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