Hybrid systems of a semiconductor (SC) and nanostructured ferromagnets (FMs) have attracted great interest, since they allow a local control of the spin property of the SC charge carriers. Several routes are being followed to obtain a spin polarization in such hybrids, including spin injection, ferromagnetic proximity polarization or the usage of local magnetic fields. We present a scheme that employs the magnetic fringe field from nanoscale FMs with a well defined magnetization to locally manipulate the spin states in a ZnCdMnSe/ZnSe dilute magnetic semiconductor quantum well (DMS QW) both incoherently and coherently.

We demonstrate a spin analogon to the "classical" electric gate: instead of electric fields which control the local charge density, magnetic fields arising from Fe/Tb nanomagnets with remanent out-of-plane magnetization are used to locally accumulate spins of a defined orientation in a SC. In an optimized hybrid structure we obtain a spatially confined, remanent spin polarization of 12 % at 4 K. The spin polarization can be switched via magnetization of the FMs and can be observed up to a sample temperature of 80 K. Highly spatially resolved photoluminescence measurements allow a local scan of the spin polarization on a sub-micrometer scale.

By using time resolved Kerr rotation measurements, we are able to demonstrate the impact of the magnetic fringe field on the coherent magnetization dynamics in the DMS QW: Fringe fields arising from nanostructured Co FMs on top of the SC effectively modify the total magnetic field, which results in a local variation of the Mn spin precession frequency. We demonstrate that even tiny fringe fields alter the coherent spin dynamics in the SC noticeably, which implies that this technique can be used as a sensitive magnetometer for local magnetic fields.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/7952 must be provided.

1. ZnO/ZnMgO multiple quantum wells on sapphire: MBE growth, structural and lasing properties
2. Magnetotransport properties of ultrathin GaMnAs layers