Abstract
The origin of ferromagnetism in nanoparticles of nonmagnetic oxides is an interesting area of research. In the present work, transport properties of niobium thin films, with β-Ga2O3 nanoparticles embedded within them, are presented. Nanoparticles of β-Ga2O3 embedded in a Nb matrix were prepared at room temperature by radio frequency co-sputtering technique on Si (100) and glass substrates held at room temperature. The thin films deposited on Si substrates were subjected to Ar annealing at a temperature range of 600-650 C for 1 hour. Films were characterized by X-ray diffraction (XRD), Micro-Raman and elemental identification was performed with an Energy Dispersive X-ray Spectroscopy (EDS). Transport measurements were performed down to liquid helium temperatures by four-probe contact technique, showed characteristics analogous to those observed in the context of a Kondo system. A comparison of the experimental data with the theoretical formalism of Kondo and Hamann is presented. It is suggested that this behavior arises from the existence of magnetic moments associated with the oxygen vacancy defects in the nanoparticles of the nonmagnetic oxide Ga2O3.
Highlights
The Kondo effect which is characterized by logT behaviour in the temperature dependence of electrical resistivity at low temperatures, has been the subject of extensive theoretical and experimental research
This paper reports the investigations on the electrical transport properties of Ga2O3/Nb thin films, especially after post annealing the film under reducing conditions at elevated temperatures, and the experimental data has been analyzed using the theoretical formalism proposed by Kondo and Hamann.[8]
Β-Ga2O3 nanoparticles embedded in Nb thin films were deposited by RF magnetron sputtering
Summary
The Kondo effect which is characterized by logT behaviour in the temperature dependence of electrical resistivity at low temperatures, has been the subject of extensive theoretical and experimental research. It has been studied in both crystalline[1] and amorphous[2] systems with the introduction of magnetic impurities carrying a magnetic moment. Recent experiments have lent credence to the existence of a new fundamental state of magnetism, viz “Quantum Spin Liquid”[3] and Anderson, who first proposed this concept, has explored its relevance in the context of High temperature Superconductivity.[4] The topic related to the interaction of superconductivity with magnetism is of great theoretical and experimental interest and there are many interesting problems which are at the frontiers of current research. Room temperature ferromagnetism has been recently observed in nanoparticles of several nonmagnetic oxides[5] and the origin of ferromagnetism
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