Critical Role of Electrical Resistivity in Magnetoionics
The utility of electrical resistivity as an indicator of magnetoionic performance in stoichiometrically and structurally similar thin-film systems is demonstrated. A series of highly nanocrystalline cobalt nitride (Co-N) thin films (85 nm thick) with a broad range of electrical properties exhibit markedly different magnetoionic behaviors. Semiconducting, near stoichiometric CoN films show the best performance, better than their metallic and insulating counterparts. Resistivity reflects the interplay between atomic bonding, carrier localization, and structural defects, and in turn determines the strength and distribution of applied electric fields inside the actuated films. This fact, generally overlooked, reveals that resistivity can be used to quickly evaluate the potential of a system to exhibit optimal magnetoionic effects, while also opening interesting challenges. ; Financial support by the European Research Council (SPIN-PORICS 2014-Consolidator Grant, Agreement No. 648454, and the MAGIC-SWITCH 2019-Proof of Concept Grant, Agreement No. 875018), the Spanish Government (MAT2017-86357-C3-1-R and PID2020- 116844RB-C21), the Generalitat de Catalunya (2017- SGR-292 and 2018-LLAV-00032) and the European Regional Development Fund (MAT2017-86357-C3-1-R and 2018-LLAV-00032) is acknowledged. This work was partially supported by the Impulse-und Net-working fund of the Helmholtz Association (FKZ VH-VI-442 Memriox), and the Helmholtz Energy Materials Characterization Platform (03ET7015). The PALS measurements were carried out at ELBE at the Helmholtz-Zentrum DresdenRossendorf e. V., a member of the Helmholtz Association. L.A. thanks MINECO for a Ramón y Cajal Contract (RYC-2013-12640). J.S. thanks the Spanish Fábrica Nacional de Moneda y Timbre for fruitful discussions. E.M. acknowledges support as a Serra Húnter Fellow. We acknowledge service from MiNa Laboratory at IMNCSIC.
