Spintronics and magneto-optics of nanomaterials

Marcos H. D. Guimarães is an Assistant Professor at the Zernike Institute for Advanced Materials (Faculty of Science and Engineering) of the University of Groningen. He is the principal investigator (PI) of the research group Opto-Spintronics of Nanostructures, studying the interplay between light, electron charge and spin, in structures which are just a few atoms thick. In 2020 Marcos joined the Young Academy Groningen, where he aims to help and broaden the science outreach programs at the University of Groningen and the North of the Netherlands.

Marcos Guimarães studied at the Federal University of Minas Gerais in Brazil, where he obtained a Bachelor and Master degrees in Physics. He received his PhD degree in 2015 from the University of Groningen, The Netherlands. After being awarded two personal research grants, the NWO Rubicon from the Netherlands, and a Kavli Institute Fellowship from the USA, he moved to Cornell University, USA, where he expanded his research focus to other two-dimensional materials and studied them using a variety of optical and electrical techniques. In 2017 Marcos received a NWO VENI grant and returned to the Netherlands where he further extended his experimental background studying ultrafast optics in two-dimensional materials at the Eindhoven University of Technology. In February 2019 he joined the Zernike Institute for Advanced Materials as an Assistant Professor in the group of Physics of Nanodevices. In 2023 he was awarded an ERC Starting Grant (2D-OPTOSPIN). The Guimarães group research focuses on the magnetic and spintronic properties of two-dimensional materials and metallic thin films studied by magneto-optical and electrical means.

My top 3 pubs:

[1] MacNeill*, G.M. Stiehl*, M.H.D. Guimaraes, R.A. Buhrman, J. Park, and D.C. Ralph “Control of spin-orbit torques through crystal symmetry in WTe₂/ferromagnet bilayers”Nat. Phys. 13, 300 (2017).

This is the first demonstration of symmetry control over spin-orbit torques, which is an effective way to control magnetization at the nanoscale using electric currents. We showed that using a low-symmetry two-dimensional material allows for an out-of-plane antidamping torque, ideal for the switching of perpendicular magnetic anisotropy magnets, such as the ones used in modern high-density memory devices.

[2] M.H.D. Guimarães, G.M. Stiehl, D. MacNeill, N. Reynolds, and D.C. Ralph “Spin-orbit torques in NbSe₂/Ferromagnet bilayers” Nano Letters 18, 1311 (2018).

This work shows that strained two-dimensional materials can be used to allow for non-conventional spin-orbit torque symmetries. Here we showed the presence of an in-plane field-like torque, which can help on the electrical switching of perpendicular magnetic anisotropy magnets, such as the ones used in modern high-density memory devices.

[3] M.J. Meijer, J. Lucassen, R. Duine, B. Koopmans, H.J.M. Swagten, R. Lavrijsen, and M.H.D. Guimarães “Chiral Spin Spirals at the Surface of van der Waals Ferromagnet Fe₃GeTe₂” Nano Letters 20, 8563 (2020).

In this work we use a scanning electron microscopy technique to image spin spirals in the van der Waals magnet Fe3GeTe2. Spin spirals are chiral magnetic domain walls which can be used in topologically-protected magnetic data storage and processing. The initial characterization done in this work is the first step to their use in energy-efficient nanoscale memory devices.