Abstract

ZnO and doped ZnO films with non-ferromagnetic metal have been widely used as biosensor elements. In these studies, the electrochemical measurements are explored, though the electrical impedance of the system. In this sense, the ferromagnetic properties of the material can be used for multifunctionalization of the sensor element using external magnetic fields during the measurements. Within this context, we investigate the room-temperature ferromagnetism in pure ZnO and Ag-doped ZnO films presenting zigzag-like columnar geometry. Specifically, we focus on the films’ structural and quasi-static magnetic properties and disclose that they evolve with the doping of low-Ag concentrations and the columnar geometry employed during the deposition. The magnetic characterization reveals ferromagnetic behavior at room temperature for all studied samples, including the pure ZnO one. By considering computational simulations, we address the origin of ferromagnetism in ZnO and Ag-doped ZnO and interpret our results in terms of the Zn vacancy dynamics, its substitution by an Ag atom in the site, and the influence of the columnar geometry on the magnetic properties of the films. Our findings bring to light an exciting way to induce/explore the room-temperature ferromagnetism of a non-ferromagnetic metal-doped semiconductor as a promising candidate for biosensor applications.

Highlights

  • We investigate the origin of ferromagnetism in ZnO and Ag-doped ZnO and interpret our results in terms of the Zn vacancy dynamics and its substitution by an Ag atom in the site and columnar structure employed during the deposition

  • Our findings provide the exciting ability of ZnO films and their capacity to compose multifunctional systems

  • We have addressed the origin of ferromagnetism in ZnO and Ag-doped ZnO and interpreted our results in terms of the Zn vacancy dynamics and its substitution of an Ag atom in the site

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Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Rare studies consider the columnar structure’s influence on the magnetic response of ZnO and doped ZnO:NFM materials In this sense, the employment of reactive magnetron sputtering associated with Glancing Angle Deposition (GLAD) emerges as an interesting experimental mechanism to produce a system with controllable columnar structure [26]. The last, in particular, brings advantages of control, not just the structural properties of the studied films, and to modify/control their electrical and magnetic properties [27,28,29], essential properties to optimize the response of future sensor elements Looking in this direction, our group has recently shown the RTFM in ZnO:Ag-doped system with high Ag concentrations has been considered. Our findings provide the exciting ability of ZnO films and their capacity to compose multifunctional systems

Experiment
Computational Simulation
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