Autor: rafa

 

«Magnetic Nano- and Microwires: Design, Synthesis, Properties and Applications»

2nd Edition, edited by Manuel Vázquez

ISBN: 9780081028322 (Woodhead Publishing, Elsevier) (2020), pp. 962

A Volume in the Woodhead Publishing Series in Electronic and Optical Materials. The most comprehensive reference available on magnetic nanowires and microwires.

Flyer of the Book

KEY FEATURES

• Details the multiple key techniques for the growth, processing and characterization of nanowires and microwires
• Discusses magnetism and transport in nanowires, skyrmions and domain walls in nano and microwires and the latest innovations in magnetic imaging
• Reviews the principles and difficulties involved in applying magnetic nano- and microwires to a wide range of technologies, including biomedical and sensing applications

DESCRIPTION

Magnetic Nano-and Microwires: Design, Synthesis, Properties and Applications, Second Edition, reviews the growth and processing of nanowires and nanowire heterostructures using such methods as electrodeposition and sol-gel, focused-electron/ion-beam-induced deposition, epitaxial growth by chemical vapor transport, and ultrafast solidification. Other sections cover engineering nanoporous anodic alumina, discuss magnetic and transport properties, domains, domain walls in nano-and microwires, and provide updates on skyrmions, domain walls, magnetism and transport, and the latest techniques to characterize and analyze these effects.

Final sections cover applications, both current and emerging, and new chapters on memory, sensor, thermoelectric and nanorobotics applications. This book will be an ideal resource for academics and industry professionals working in the disciplines of materials science, physics, chemistry, electrical and electronic engineering and nanoscience.

 

 

“Nanopatterned hard/soft bilayer magnetic antidot arrays with long-range periodicity”

Andreas Kaidatzis, Rafael P. del Real, Raquel Alvaro, Dimitrios Niarchos, Manuel Vázquez, José Miguel García-Martín

J. Magn. Magn. Mater., 2019, 166142

DOI: https://doi.org/10.1016/j.jmmm.2019.166142

 

A top-down approach using focused ion beam has been employed to fabricate Co/Permalloy hard-soft bilayer magnetic antidot arrays. These nanopatterned films are studied with particular emphasis on magnetic coercivity. The antidots have a diameter of 40 nm and the studied antidot symmetries are square and hexagonal. A dependence of magnetic coercivity on the relative thicknesses of the magnetically hard (Co) and soft (Permalloy) layers is found; increasing Permalloy thickness results in lower magnetic coercivity. Furthermore, the long-range periodicity of top-down nanopatterned antidots results in higher magnetic coercivity and a stronger magnetic domain-wall pinning, compared to identical hard/soft bilayers of short-range order deposited on porous anodic alumina. The combination of antidot symmetry and hard/soft thickness, allow for efficient tailoring of the magnetic properties of nanopatterned thin films. Finally, magnetic force microscopy imaging of the antidot array magnetic configuration shows striking qualitative differences between the two array symmetries: square symmetry arrays have inhomogeneous magnetic state and a high density of immobile super-domain walls, whereas hexagonal symmetry arrays show a homogeneous magnetic configuration.

We show in the figure a representative MOKE hysteresis loops of antidot arrays. Square (left) and hexagonal (right) symmetries of the Co/Py-thin bilayer; the lattice constant is 240 nm; first and second neighbor directions, denoted by the angles, are shown: 0º and 45º, respectively, for the square array, and 0º and 30º, respectively, for the hexagonal array

 

This paper derives from a previous international collaboration funded by CSIC (Ref. i-LINK0783).  This study has been supported by the Comunidad de Madrid under  projects S2018/NMT-4291 TEC2SPACE and S2018/NMT-4321 NANOMAGCOST, and the Spanish MINECO under projects CSIC13-4E-1794 and MAT2016-76824-C3-1-R.

 

“Time-resolved motion of a single domain wall controlled by a local tunable barrier”

Esther Calle, Manuel Vázquez and Rafael Pérez del Real

J. Magn. Magn. Mater., 2019, 166142

DOI: https://doi.org/10.1016/j.jmmm.2019.166093

 

We report on the time-resolved dynamics of a single magnetic domain wall (DW) under the influence of a tunable barrier in a Fe-rich microwire. The energy barrier was created by applying a local magnetic field antiparallel to the uniform driving field used to depin and propagate the DW along the wire. This originates the braking and eventually the trapping of the DW depending on the magnitude of the antiparallel local field. The motion of the DW through the local field becomes stochastic for minimum magnetic field values close to the measured friction field (Hfr=24.4A/m). This phenomenon is caused by fluctuations in the pinning field associated to the different

types of local defects and residual stress existing in the wire. The probability for the DW to overcome the barrier has been estimated for different values of the local field. When the minimum applied field is lower than the fluctuating friction field the DW is always trapped.

In the figure we show the time-resolved DW velocity for Hprim=90.5A/m and Hmin=35.6A/m. Different colors mean the different stages during the nucleation and propagation of the DW: orange the nucleation and acceleration, pale pink the movement at steady velocity, blue the braking by the local field and green the braking and stopping when it is close to the end of the primary coil.

 

This work has been supported by the Spanish National Research Council under CSIC Project No. 201760E040 and by Comunidad Autónoma de Madrid under Project S2018/NMT-4321 NANOMAGCOST

Alexander Valeriano Inchausti is incorporated to the group to perform research on Magnetism of Microwires focused towards his Master Thesis, TFM. Alex is enrolled as Master student of Physics of the Condensed Mater and Biological Systems, at the Faculty of Physics, Autonomous University of Madrid.