Density-controlled quantum Hall ferromagnetic transition in a two-dimensional hole system

Abstract Quantum Hall ferromagnetic transitions are typically achieved by increasing the Zeeman energy through in-situ sample rotation, while transitions in systems with pseudo-spin indices can be induced by gate control. We report here a gate-controlled quantum Hall ferromagnetic transition between...

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Auteurs principaux: T. M. Lu, L. A. Tracy, D. Laroche, S.-H. Huang, Y. Chuang, Y.-H. Su, J.-Y. Li, C. W. Liu
Format: article
Langue:EN
Publié: Nature Portfolio 2017
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Accès en ligne:https://doaj.org/article/3650b9ac5e904b8392c3e5a072007ba9
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Résumé:Abstract Quantum Hall ferromagnetic transitions are typically achieved by increasing the Zeeman energy through in-situ sample rotation, while transitions in systems with pseudo-spin indices can be induced by gate control. We report here a gate-controlled quantum Hall ferromagnetic transition between two real spin states in a conventional two-dimensional system without any in-plane magnetic field. We show that the ratio of the Zeeman splitting to the cyclotron gap in a Ge two-dimensional hole system increases with decreasing density owing to inter-carrier interactions. Below a critical density of ~2.4 × 1010 cm−2, this ratio grows greater than 1, resulting in a ferromagnetic ground state at filling factor ν = 2. At the critical density, a resistance peak due to the formation of microscopic domains of opposite spin orientations is observed. Such gate-controlled spin-polarizations in the quantum Hall regime opens the door to realizing Majorana modes using two-dimensional systems in conventional, low-spin-orbit-coupling semiconductors.