Group of Nanomagnetism and Magnetization Processes

“Magnetic microwires for energy-transporting biomedical applications”

US Patent Application Pub.No. US 2021/0101016 A1; Northeastern University, Boston and CSIC

Inventors: L.H. Lewis, R. P. del Real, M. Vazquez Villalabeitia and A.N. Koppes

Methods and devices including amorphous magnetic microwires are provided for biomedical energy transfer for diagnosis or therapy, to promote cellular growth, or to deliver pharmaceutical agents. Applications of the technology include sensors, actuators and therapeutic coatings and for increasing the amount, directionally, or length of nerve growth. The technology can also be utilized for nerve regeneration, hyperthermic treatment of tumors, vascular theranostics, probing and stimulating a nerve, sensing a biological condition, catheterization and micro-actuation.

This patent application is the result of a continuous collaboration of our GNMP group with the Northeastern University of Boston.

“Evidence of Skyrmion-Tube Mediated Magnetization Reversal in Modulated Nanowires”

E. Berganza, J. Marqués-Marchán, C. Bran, M. Vazquez, A. Asenjo and M. Jaafar

 Materials 14 (2021) 5671

DOI://doi.org/10.3390/ma14195671

Magnetic nanowires, as individual building blocks for spintronic devices, constitute a well-suited model to design and study magnetization reversal processes, or to tackle fundamental questions, as the presence of topologically protected magnetization textures under particular conditions. Recently, a skyrmion-tube mediated magnetization reversal process was theoretically reported in diameter modulated cylindrical nanowires where a vortex nucleates at the end of the segments with larger diameter and propagates, resulting in a first switching of the nanowire core magnetization at small fields. Here, we show experimental evidence of the so-called Bloch skyrmion-tubes, using advanced Magnetic Force Microscopy modes to image the magnetization reversal process of FeCoCu diameter modulated nanowires. By monitoring the magnetic state during applied field sweeping, a detected drop of magnetic signal at a given critical field unveils the presence of a skyrmion-tube, due to mutually compensating stray field components.

This study is a collaboration between our GNMP group and the Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Germany and the Departamento de Física de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), and the Instituto Nicolás Cabrera, at the Universidad Autónoma de Madrid.

“Stochastic vs. deterministic magnetic coding in designed cylindrical nanowires for 3D magnetic networks”

C. Bran, E. Saugar, J.A. Fernandez-Roldan, R.P. del Real, A. Asenjo, L. Aballe, M. Foerster, A. Fraile Rodríguez, E.M. Palmero, M. Vazquez and O. Chubykalo-Fesenko

Nanoscale 13 (2021) 12587

DOI: 10.1039/d1nr02337c

 

Advances in cylindrical nanowires for 3D information technologies profit from intrinsic curvature that introduces significant differences with regards to planar systems. A model is proposed to control the stochastic and deterministic coding of remanent 3D complex vortex configurations in designed multilayered (magnetic/non-magnetic) cylindrical nanowires. This concept, introduced by micromagnetic simulations, is experimentally confirmed by magnetic imaging in FeCo/Cu multilayered nanowires. The control over the random/deterministic vortex states configurations is achieved by a suitable geometrical interface tilting of almost non-interacting FeCo segments with respect to the nanowire axis, together with the relative orientation of the perpendicular magnetic field. The proper design of the segments’ geometry (e.g. tilting) in cylindrical nanowires opens multiple opportunities for advanced nanotechnologies in 3D magnetic networks.

This work has been performed in collaboration between our GNMP group at ICMM/CSIC with ALBA Synchrotron Light Facility, CELLS, Barcelona, the Departament de Física de la Matèria Condensada, Universitat de Barcelona and the Group of Permanent Magnets and Applications, IMDEA Nanoscience, Madrid. It has been supported by the Spanish Ministry of Science and Innovation under Projects MAT2016-76824-C3-1-R, PID2019-108075RB-C31/AEI /10.13039/501100011033 and PGC2018-097789-B-I00 and the Regional Government of Madrid under Project S2018/NMT-4321 NANOMAGCOST-CM.