Soft inter-Landau-level spin-flip magnetoexciton as a precursor of ferromagnetic instability

被引：19

作者：

Van'kov, A. B. ^{[1
,2
]}

Kaysin, B. D. ^{[1
]}

Kukushkin, I., V ^{[1
,2
]}

机构：

[1] RAS, Inst Solid State Phys, Chernogolovka 142432, Russia

[2] Natl Res Univ, Higher Sch Econ, Lab Condensed Matter Phys, Moscow 101000, Russia

来源：

PHYSICAL REVIEW B | 2018年 / 98卷 / 12期

基金：

俄罗斯科学基金会;

关键词：

COLLECTIVE EXCITATIONS; ELECTRON-GAS;

D O I：

10.1103/PhysRevB.98.121412

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We investigate the impact of Coulomb correlations on the low-energy collective excitations in two-dimensional electron systems in the quantum Hall state nu = 2. The collective excitations are studied using inelastic light scattering in the set of MgZnO/ZnO heterostructures with high-mobility two-dimensional electrons. The study focuses on the lowest-energy collective excitations in the paramagnetic state nu = 2, the cyclotron spin-flip magnetoexcitons (CSFMs), which are associated with inter-Landau-level transitions with a simultaneous spin flip. The Coulomb contribution to the CSFM energy is measured independently of the Zeeman term as a function of electron density. It is established that in the range of electron concentrations corresponding to the Wigner-Seitz parameter r(s) similar to 5-7, the combination of the Coulomb and Zeeman contributions leads to a softening of the CSFM. This softening accompanies spontaneous switching of the spin configuration in the nu = 2 quantum Hall system from paramagnetic to ferromagnetic. Theoretical estimates are given for the correlation energy terms of the CSFM responsible for its softening and a concomitant ferromagnetic transition.

引用

页数：5