Picosecond Switching of Optomagnetic Tunnel Junctions

Towards coherent optical control of a single hole spin: Rabi rotation of a trion conditional on the spin state of the hole

A hole spin is a potential solid-state q-bit, that may be more robust against nuclear spin induced dephasing than an electron spin. Here we propose and demonstrate the sequential preparation, control and detection of a single hole spin trapped on a self-assembled InGaAs/GaAs quantum dot. The dot is embedded in a photodiode structure under an applied electric-field. Fast, triggered, initialization of a hole spin is achieved by creating a spin-polarized electron-hole pair with a picosecond laser pulse, and in an applied electric-field, waiting for the electron to tunnel leaving a spin-polarized …

Longitudinal and transverse spin relaxation times of magnetic single adatoms: an ab initio analysis

We present a systematic ab initio investigation of the longitudinal and transverse spin relaxation times of magnetic single adatoms deposited on metallic substrates. Our analysis based on time-dependent density functional theory shows that the longitudinal time, $T_{\parallel}$, is of order femtosecond while the transverse time, $T_{\perp}$, is of order picosecond, i.e. $T_{\perp}\gg T_{\parallel}$. This comes as a consequence of the different energy scales of the corresponding processes: $T_{\parallel}$ involves spin-density excitations of order eV, while $T_{\perp}$ is governed by atomic spi…

Ultrafast Spin-Transfer-Torque Switching of Synthetic Ferrimagnets

The switching speed and the write current required for spin-transfer-torque reversal of spintronic devices such as magnetic tunnel junctions (MTJ) currently hinder their wide implementation into memory and logic devices. This problem is further exacerbated as the dimensions of MTJ nanostructures are scaled down to tens of nanometers in diameter, as higher magnetic anisotropy materials are required to meet thermal stability requirements that demand higher switching current densities. Here, we propose a simple solution to these issues based on synthetic ferrimagnet (SFM) structures. It is common…

单个飞秒激光脉冲驱动的铁磁翻转

Single femtosecond laser pulse-driven ferromagnetic switching

本文报告了在铁磁体中利用热各向异性扭矩实现单激光脉冲驱动的相干磁化翻转，该翻转在飞秒到皮秒脉冲范围内稳健，且在CoFeB/MgO磁性隧道结中表现出超过110%的磁阻和优异能效，推动了光自旋电子学在内存技术中的应用。