发表机构
Islamic Azad University; Farhangian University; Imam Khomeini International University; Indian Statistical Institute（伊斯兰阿扎德大学; 法尔坎吉安大学; 伊玛目霍梅尼国际大学; 印度统计研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过非绝热量子泵浦在反铁磁链中实现近纯自旋流产生，利用时间依赖势和Keldysh格林函数方法，通过调节化学势和频率控制自旋流大小与方向，实现无净电荷转移的自旋泵浦。
AI 中文摘要
本研究探讨了由时间依赖势驱动的反铁磁链中的量子自旋泵浦。其目标是探索在无外部偏压条件下产生和控制自旋流的可能性，并考察交换场和周期性驱动在自旋向上与自旋向下电流分离中的作用。系统采用紧束缚模型描述，并利用Keldysh非平衡格林函数形式计算自旋分辨电流。在链的两端施加两个具有特定相位差的时间依赖势，同时两个电极的化学势设置为相等。结果表明，在绝热区（低频）内，两个自旋通道的响应几乎相同。然而，随着驱动频率增加，系统进入非绝热区，能量量子的吸收和发射过程被激活，导致自旋向上与自旋向下电流之间出现显著差异。泵浦电流对化学势表现出强烈依赖，从而可通过调节化学势来控制自旋流的大小和方向。随着频率增加，自旋流增强，并且可调节参数使电荷流几乎消失而显著的自旋流持续存在。这一发现表明，在反铁磁链中实现无净电荷转移的近纯自旋泵浦是可行的。该结果为基于反铁磁系统设计自旋泵浦器件提供了有前景的视角。
英文摘要
In this study, quantum spin pumping in an antiferromagnetic chain driven by time-dependent potential is investigated. The aim is to explore the possibility of generating and controlling spin currents in the absence of external bias and to examine the role of exchange field and periodic driving in the separation of spin-up and spin-down currents. The system is described using a tight-binding model, and spin-resolved currents are calculated employing the Keldysh non-equilibrium Green's function formalism. Two time-dependent potentials with a specific phase difference are applied to the two ends of the chain, while the chemical potentials of both electrodes are set equal. The results demonstrate that in the adiabatic regime (low frequencies), the response of the two spin channels is nearly identical. However, as the driving frequency increases and the system enters the nonadiabatic regime, absorption and emission processes of energy quanta become activated, leading to significant differences between spin-up and spin-down currents. The pumped current exhibits strong dependence on the chemical potential, allowing for the control of both magnitude and direction of the spin current through its adjustment. With increasing frequency, the spin current enhances, and parameters can be tuned such that the charge current nearly vanishes while a considerable spin current persists. This finding indicates the feasibility of achieving nearly pure spin pumping without net charge transfer in the antiferromagnetic chain. The results provide a promising perspective for designing spin-pumping devices based on antiferromagnetic systems.
Comments17 pages, 6 figures
