Jose A. Fernandez-Roldan
Scientific researcher.
PhD in Condensed Matter Physics, Nanoscience and Biophysics
In a nutshell, who am I?
I am postdoctoral scientific researcher with a background on physics and modelling in 3D nanomagnetism in the group of Dr. Denys Makarov at Helmholtz Zentrum Dresden-Rossendorf, HZDR as fellow of the Alexander von Humboldt Foundation.
I started my career as FPI fellow of the Spanish Government in the group of Manuel Vazquez, Agustina Asenjo, Rafael Perez del Real, and Oksana Chubykalo-Fesenko at the Institute of Materials Science of Madrid (ICMM-CSIC) and got my PhD in 2019 . During my PhD I obtained funding for visits to the Institute Néel with Olivier Fruchart and Daria Gusakova in 2016 and the Leibniz Institute for Solid State and Materials Research -IFW (Germany) in 2017.
As a postdoc at the University of Oviedo (Spain) in the group of Victor Manuel de la Prida and Javier Garcia I have visited Karlsruhe Institute of Technology (KIT) with a KHYS grant, and I was a guest scientist in the group of Denys Makarov at Helmholtz Zentrum Dresden-Rossendorf. I was awarded with the IEEE Magnetics Society Educational Seed Fund in 2020 . I chaired the IEEE ‘2021 Around-the-world Around-the-clock International Magnetics Conference’, as well as organized and co-chaired the ‘4th and 5th Young Researchers in Magnetism’ Conference respectively. I also manage the recent joint YouTube channel of the Spanish Magnetism Club and the Spanish chapter of IEEE Mag Soc.
My research focuses on computational micromagnetic modelling of challenging bottlenecks in spintronic applications based on magnetic 3D nanostructures, as well as assistance in the interpretation of advanced techniques, such as synchrotron imaging (XMCD-PEEM, TXM, MFM, etc.). I have also assisted measurements at ALBA and Elletra.
Read more about me here, in my 2-page CV and my photo gallery.
News and recent activities
i-Skyrmion.avi
E. Berganza, J.A. Fernandez-Roldan, M. Jaafar, A. Asenjo, K. Guslienko, and O. Chubykalo-Fesenko. 3D quasi-skyrmions in thick cylindrical and dome-shape soft nanodots. Sci. Rep. Scientific Reports 12, 3426 (2022). DOI:10.1038/s41598-022-07407-w
"...We demonstrate the possibility to stabilize Néel skyrmions in both planar and dome-shape thick nanodots with no need of special material, i.e., with no DMI and no perpendicular anisotropy..." This study paths a way to develop spintronic applications based on skyrmionic structures in intrinsic DMI-free materials.
Videos of several magnetic states in nanodots here.
Presentation in the onsite Joint MMM-Intermag 2022 Conference, New Orleans, USA. Video available in underline.io. HOH-06, Oersted-field- and current- induced Bloch Point domain wall dynamics in cylindrical Ni nanowires.
In this talk I introduce my results on Bloch Point wall dynamics in cylindrical nanowires for spintronic and magnetic recording applications. Importantly, we consider both, spin-polarized current and Oersted field, which have not been included up to know.
J. García, J. A. Fernandez-Roldan, R. González, M. Méndez, C. Bran, V. Vega, S. González, M. Vázquez and V. M. Prida. Narrow segment driven multistep magnetization reversal process in sharp diameter modulated Fe67Co33 nanowires. Nanomaterials 11(11), 3077 (2021). DOI:10.3390/nano11113077
"...these results ... suggest that single sharp geometrical modulations are sufficient to induce skyrmion-like structures in cylindrical nanowires with large saturation magnetization. This is of major importance for the development of applications based on 3D nanomagnetism and spintronic applications of topologically non-trivial spin-textures."
Research lines
Micromagnetic modeling and design of 3D magnetic nanostructures (nanowires, nanotubes and dots) for spintronics and magnetic recording applications. This includes magnetization and domain wall dynamics under magnetic fields and spin-polarized currents.
Curvature-induced (intrinsic DMI-free) skyrmions and non-trivial topologies in magnetic curved nanostructures.
Design of nanostructures and interpretation of imaging and synchrotron techniques through modelling : XMCD-PEEM, TXM, MFM, etc. I have participated in synchrotron experiments in ALBA (BCN) and Elletra (Trieste)
Bio-applications of magnetic nanostructures: Magnetic hyperthermia, water purification, etc.
Lithography and magnetotransport measurements in magnetic nanostructures with Heidelberg µPG 101 laser writer and PPMS Dynacool.