Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

Nov. 16, 2017 at 2:15 p.m. in MEDIEN-Room, Staudinger Weg 7, 03-431Univ-Prof. Dr. Jure Demsar

Univ.-Prof. Dr. Hans-Joachim Elmers

Univ.-Prof. Dr. Mathias Kläui

Univ.-Prof. Dr. Thomas Palberg

Dr. Nicolas Reyren (Unité Mixte de Physique CNRS/Thales, France)

Spintronics evolves along new paths involving non-magnetic materials having large spin-obit coupling, typically 5d metals, allowing, for example, large spin-to-charge current conversion (spin Hall and Rashba-Edelstein effects). These heavy metals have other effects: in proximity of magnetic thin films they can burst out the Dzyaloshinskii-Moriya interaction (DMI) leading to the stabilization of chiral magnetic structures. This DMI has several consequences for technological applications such as favoring Néel domain walls, which are easier to move using spin-orbit torques in materials with perpendicular magnetization [1]; or stabilizing magnetic skyrmions, extremely small magnetic textures with a particular topology.

During this seminar, we will review some of our recent results illustrating the role of the DMI. In the first part, we will discuss both experimentally and theoretically a new in-plane anisotropy, which is orthogonal to the shape demagnetization anisotropy [2]. In a second part, we discuss, based on numerical simulations, the detrimental role of the Dzyaloshinskii-Moriya interaction in MRAM structures with perpendicular magnetization, and in particular, how it reduces the thermal stability and increases the switching current [3]. We will finally present our recent progresses concerning magnetic skyrmions [4]. We showed that skyrmions can be stabilized at room temperature [5], and furthermore that they can be moved using spin-orbit torques. The presence of grains or variable properties (including DMI magnitude) can explain the complex motion that we observed [6].