Beatings of ratchet current magneto-oscillations in GaN-based grating gate structures: Manifestation of spin-orbit band splitting

OPEN DATA related to the research publication:

Sai, P., Potashin, S. O., Szoła, M., Yavorskiy, D., Cywiński, G., Prystawko, P., ... & Kachorovskii, V. Y. (2021). Beatings of ratchet current magneto-oscillations in GaN-based grating gate structures: Manifestation of spin-orbit band splitting. Physical Review B, 104(4), 045301 [arXiv:2102.12791].

Abstract: We report on the study of the magnetic ratchet effect in AlGaN/GaN heterostructures superimposed with a lateral superlattice formed by a dual-grating gate structure. We demonstrate that irradiation of the superlattice with a terahertz beam results in the direct ratchet current, which shows giant magneto-oscillations in the regime of Shubnikov–de Haas oscillations. The oscillations have the same period and are in phase with the resistivity oscillations. Remarkably, their amplitude is greatly enhanced as compared with the ratchet current at zero magnetic field, and the envelope of these oscillations exhibits large beatings as a function of the magnetic field. We demonstrate that the beatings are caused by the spin-orbit (SO) splitting of the conduction band. We develop a theory which gives a good qualitative explanation of all experimental observations and allows us to extract the SO splitting constant αSO=7.5±1.5 meVÅ. We also discuss how our results are modified by plasmonic effects and show that these effects become more pronounced with decreasing the period of the grating gate structures down to submicrons.

本公开数据集关联如下研究论文：
赛（P. Sai）、波塔申（S. O. Potashin）、索拉（M. Szoła）、亚沃尔斯基（D. Yavorskiy）、齐温斯基（G. Cywiński）、普里斯塔夫科（P. Prystawko）等人（2021年）. 基于氮化镓（GaN）的栅极光栅结构中棘轮电流磁振荡的拍频现象：自旋轨道（spin-orbit, SO）能带劈裂的体现. 《物理评论B辑》（Physical Review B）, 104卷第4期, 045301, 预印本编号arXiv:2102.12791.

摘要：
本研究针对搭载有由双栅门结构（dual-grating gate structure）构筑的横向超晶格（lateral superlattice）的铝镓氮/氮化镓（AlGaN/GaN）异质结构中的磁棘轮效应（magnetic ratchet effect）开展研究并报告相关结果。我们发现，利用太赫兹光束（terahertz beam）辐照该超晶格可诱导产生直接棘轮电流（direct ratchet current），该电流在舒布尼科夫-德哈斯（Shubnikov–de Haas）振荡工况下呈现出巨幅磁振荡现象。该磁振荡与电阻率振荡周期一致且相位同步。值得注意的是，相较于零磁场下的棘轮电流，该磁振荡的振幅得到了显著提升，且其包络线随磁场变化呈现出明显的拍频特性。我们证实，该拍频特性源于导带的自旋轨道（SO）能带劈裂。我们构建了一套理论模型，可对所有实验观测结果给出合理的定性解释，并借此提取出自旋轨道劈裂常数α_SO=7.5±1.5 毫电子伏特·埃（meVÅ）。我们还探讨了等离子体激元（plasmonic）效应对本研究结果的调控作用，并证实当栅极光栅结构的周期降至亚微米（submicrons）级别时，该效应会愈发显著。