Next Article in Journal
Anneal-Hardening Behavior of Cr-Fe-C Alloy Deposits Prepared in a Cr3+-Based Bath with Fe2+ Ions
Next Article in Special Issue
Magnetization Reversal Modes in Short Nanotubes with Chiral Vortex Domain Walls
Previous Article in Journal
Alkaline Materials and Regenerative Endodontics: A Review
Previous Article in Special Issue
Magnetic Hysteresis in Nanocomposite Films Consisting of a Ferromagnetic AuCo Alloy and Ultrafine Co Particles
Article Menu
Issue 12 (December) cover image

Export Article

Open AccessFeature PaperArticle
Materials 2017, 10(12), 1390; https://doi.org/10.3390/ma10121390

Structurally Oriented Nano-Sheets in Co Thin Films: Changing Their Anisotropic Physical Properties by Thermally-Induced Relaxation

1
Laboratorio de Magnetismo, Departamento de Física, Universidad Pública de Navarra, 31006 Pamplona, Spain
2
Instituto de Materiales Avanzados, Universidad Pública de Navarra, 31006 Pamplona, Spain
3
Instituto de Nanociencia de Aragón (INA) and Laboratorio de Microscopías Avanzadas (LMA), Universidad de Zaragoza, 50018 Zaragoza, Spain
4
Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
5
Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain
*
Author to whom correspondence should be addressed.
Received: 30 October 2017 / Revised: 24 November 2017 / Accepted: 29 November 2017 / Published: 5 December 2017
(This article belongs to the Special Issue Advances in Superconductive and Magnetic Nanomaterials)
Full-Text   |   PDF [9670 KB, uploaded 5 December 2017]   |  

Abstract

We show how nanocrystalline Co films formed by separated oblique nano-sheets display anisotropy in their resistivity, magnetization process, surface nano-morphology and optical transmission. After performing a heat treatment at 270 °C, these anisotropies decrease. This loss has been monitored measuring the resistivity as a function of temperature. The resistivity measured parallel to the direction of the nano-sheets has been constant up to 270 °C, but it decreases when measured perpendicular to the nano-sheets. This suggests the existence of a structural relaxation, which produces the change of the Co nano-sheets during annealing. The changes in the nano-morphology and the local chemical composition of the films at the nanoscale after heating above 270 °C have been analysed by scanning transmission electron microscopy (STEM). Thus, an approach and coalescence of the nano-sheets have been directly visualized. The spectrum of activation energies of this structural relaxation has indicated that the coalescence of the nano-sheets has taken place between 1.2 and 1.7 eV. In addition, an increase in the size of the nano-crystals has occurred in the samples annealed at 400 °C. This study may be relevant for the application in devices working, for example, in the GHz range and to achieve the retention of the anisotropy of these films at higher temperatures. View Full-Text
Keywords: nanocrystals; anisotropy resistivity; magnetic; optic; morphological; nano-sheets; STEM-EELS; structural relaxation; activation energy; laser deposition PLD nanocrystals; anisotropy resistivity; magnetic; optic; morphological; nano-sheets; STEM-EELS; structural relaxation; activation energy; laser deposition PLD
Figures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Vergara, J.; Favieres, C.; Magén, C.; de Teresa, J.M.; Ibarra, M.R.; Madurga, V. Structurally Oriented Nano-Sheets in Co Thin Films: Changing Their Anisotropic Physical Properties by Thermally-Induced Relaxation. Materials 2017, 10, 1390.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Materials EISSN 1996-1944 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top