A1 Refereed original research article in a scientific journal
Manipulating magnetic and magnetoresistive properties by oxygen vacancy complexes in GCMO thin films
Authors: Beiranvand Azar, Liedke Maciej Oskar, Haalisto Christopher, Lähteenlahti Ville, Schulman Alejandro, Granroth Sari, Palonen Heikki, Butterling Maik, Wagner Andreas, Huhtinen Hannu, Paturi Petriina
Publisher: IOP Publishing Ltd
Publication year: 2022
Journal: Journal of Physics: Condensed Matter
Journal name in source: JOURNAL OF PHYSICS-CONDENSED MATTER
Journal acronym: J PHYS-CONDENS MAT
Article number: 155804
Volume: 34
Issue: 15
Number of pages: 10
ISSN: 0953-8984
DOI: https://doi.org/10.1088/1361-648X/ac4eac
Web address : https://iopscience.iop.org/article/10.1088/1361-648X/ac4eac
Abstract
The effect of in situ annealing is investigated in Gd0.1Ca0.9MnO3 (GCMO) thin films in oxygen and vacuum atmospheres. We show that the reduction of oxygen content in GCMO lattice by vacuum annealing induced more oxygen complex vacancies in both subsurface and interface regions and larger grain domains when compared with the pristine one. Consequently, the double exchange interaction is suppressed and the metallic-ferromagnetic state below Curie temperature turned into spin-glass insulating state. In contrast, the magnetic and resistivity measurements show that the oxygen treatment increases ferromagnetic phase volume, resulting in greater magnetization (M (S)) and improved magnetoresistivity properties below Curie temperature by improving the double exchange interaction. The threshold field to observe the training effect is decreased in oxygen treated film. In addition, the positron annihilation spectroscopy analysis exhibits fewer open volume defects in the subsurface region for oxygen treated film when compared with the pristine sample. These results unambiguously demonstrate that the oxygen treated film with significant spin memory and greater magnetoresistance can be a potential candidate for the future memristor applications.
The effect of in situ annealing is investigated in Gd0.1Ca0.9MnO3 (GCMO) thin films in oxygen and vacuum atmospheres. We show that the reduction of oxygen content in GCMO lattice by vacuum annealing induced more oxygen complex vacancies in both subsurface and interface regions and larger grain domains when compared with the pristine one. Consequently, the double exchange interaction is suppressed and the metallic-ferromagnetic state below Curie temperature turned into spin-glass insulating state. In contrast, the magnetic and resistivity measurements show that the oxygen treatment increases ferromagnetic phase volume, resulting in greater magnetization (M (S)) and improved magnetoresistivity properties below Curie temperature by improving the double exchange interaction. The threshold field to observe the training effect is decreased in oxygen treated film. In addition, the positron annihilation spectroscopy analysis exhibits fewer open volume defects in the subsurface region for oxygen treated film when compared with the pristine sample. These results unambiguously demonstrate that the oxygen treated film with significant spin memory and greater magnetoresistance can be a potential candidate for the future memristor applications.
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