scholarly journals Magneto-Transport Properties of Co–Cu Thin Films Obtained by Co-Sputtering and Sputter Gas Aggregation

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 134
Author(s):  
Ricardo López Antón ◽  
Juan Pedro Andrés ◽  
Mihail Ipatov ◽  
Juan Antonio González ◽  
Julián González ◽  
...  

Cu100−xCox thin films have been obtained by sputtering (x = 3, 9) and sputter gas aggregation (x = 2.5, 7.5) and subsequent annealing at 400 °C for 1 h. We have studied their structural, magnetic, and magnetotransport properties, both for the as-deposited and annealed samples, confirming the important role of the fabrication method in the properties. The magnetic measurements and the fitting of the hysteresis loops evidence that as-deposited samples consist of superparamagnetic (SPM) and/or ferromagnetic clusters, but in the samples obtained by gas aggregation the clusters are greater (with ferromagnetic behavior at room temperature) whereas in the samples obtained by sputtering, the clusters are smaller and there are also diluted Co atoms in the Cu matrix. The annealing affects negligibly the samples obtained by gas aggregation, but the ones obtained by sputtering are more affected, appearing greater clusters. This behavior is also reflected in the magnetoresistance (MR) measurements of the samples, with different shapes of the MR curves depending on the preparation method: more lineal in the whole range for sputtering, saturation at low fields (about 10 kOe) for gas aggregation. Finally, a Kondo-like minimum in the resistance versus temperature is found in the samples obtained by sputtering, affected by the magnetic field and the annealing. The observed Kondo-like behavior and the influence of annealing on a Kondo-like minimum in sputtered thin films have been attributed to the presence of diluted Co atoms in the Cu matrix and the Co precipitations from the Co–Cu solid solution upon annealing respectively.

2020 ◽  
Vol 16 (4) ◽  
pp. 655-666
Author(s):  
Mona Rekaby

Objective: The influence of Manganese (Mn2+) and Cobalt (Co2+) ions doping on the optical and magnetic properties of ZnO nanoparticles was studied. Methods: Nanoparticle samples of type ZnO, Zn0.97Mn0.03O, Zn0.96Mn0.03Co0.01O, Zn0.95Mn0.03 Co0.02O, Zn0.93Mn0.03Co0.04O, and Zn0.91Mn0.03Co0.06O were synthesized using the wet chemical coprecipitation method. Results: X-ray powder diffraction (XRD) patterns revealed that the prepared samples exhibited a single phase of hexagonal wurtzite structure without any existence of secondary phases. Transmission electron microscope (TEM) images clarified that Co doping at high concentrations has the ability to alter the morphologies of the samples from spherical shaped nanoparticles (NPS) to nanorods (NRs) shaped particles. The different vibrational modes of the prepared samples were analyzed through Fourier transform infrared (FTIR) measurements. The optical characteristics and structural defects of the samples were studied through Photoluminescence (PL) spectroscopy. PL results clarified that Mn2+ and Co2+ doping quenched the recombination of electron-hole pairs and enhanced the number of point defects relative to the undoped ZnO sample. Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM). (Mn, Co) co-doped ZnO samples exhibited a ferromagnetic behavior coupled with paramagnetic and weak diamagnetic contributions. Conclusion: Mn2+ and Co2+ doping enhanced the room temperature Ferromagnetic (RTFM) behavior of ZnO. In addition, the signature for antiferromagnetic ordering between the Co ions was revealed. Moreover, a strong correlation between the magnetic and optical behavior of the (Mn, Co) co-doped ZnO was analyzed.


2004 ◽  
Vol 95 (1) ◽  
pp. 219-225 ◽  
Author(s):  
Jung-Kun Lee ◽  
Young Hyun Lee ◽  
Kug Sun Hong ◽  
Jin-Wook Jang

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 580 ◽  
Author(s):  
Mariia Chernykh ◽  
Natalia Mikheeva ◽  
Vladimir Zaikovskii ◽  
Mikhail Salaev ◽  
Leonarda F. Liotta ◽  
...  

Ag–CeO2 catalysts (20 mol % Ag) were synthesized using different techniques (co-precipitation, impregnation, and impregnation of pre-reduced ceria), characterized by XRD, N2 sorption, TEM, H2-TPR methods, and probed in room-temperature p-nitrophenol reduction into p-aminophenol in aqueous solution at atmospheric pressure. The catalyst preparation method was found to determine the textural characteristics, the oxidation state and distribution of silver and, hence, the catalytic activity in the p-nitrophenol reduction. The impregnation technique was the most favorable for the formation over the ceria surface of highly dispersed silver species that are active in the p-nitrophenol reduction (the first-order rate constant k = 0.656 min−1).


Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 50 ◽  
Author(s):  
Sergio David Villalobos Mendoza ◽  
José Trinidad Holguín Momaca ◽  
José Trinidad Elizalde Galindo ◽  
Diana María Carrillo Flores ◽  
Sion Federico Olive Méndez ◽  
...  

Fe-doped LiTaO3 thin films with a low and high Fe concentration (labeled as LTO:Fe-LC and LTO:Fe-HC, respectively) were deposited by magnetron sputtering from two home-made targets. The dopant directly influenced the crystalline structure of the LiTaO3 thin films, causing the contraction of the unit cell, which was related to the incorporation of Fe3+ ions into the LiTaO3 structure, which occupied Li positions. This substitution was corroborated by Raman spectroscopy, where the bands associated with Li-O bonds broadened in the spectra of the samples. Magnetic hysteresis loops, zero-field cooling curves, and field cooling curves were obtained in a vibrating sample magnetometer. The LTO:Fe-HC sample demonstrates superparamagnetic behavior with a blocking temperature of 100 K, mainly associated with the appearance of Fe clusters in the thin film. On the other hand, a room temperature ferromagnetic behavior was found in the LTO:Fe-LC layer where saturation magnetization (3.80 kAm−1) and magnetic coercivities were not temperature-dependent. Moreover, the crystallinity and morphology of the samples were evaluated by X-ray diffraction and scanning electron microscopy, respectively.


2020 ◽  
Vol 846 ◽  
pp. 156368
Author(s):  
Mohammad Shahnawaze Ansari ◽  
Mohd Hafiz Dzarfan Othman ◽  
Mohammad Omaish Ansari ◽  
Sana Ansari ◽  
Huda Abdullah ◽  
...  

1998 ◽  
Vol 526 ◽  
Author(s):  
R. Kubo ◽  
H. Xu ◽  
Y. Yoshino ◽  
M. Okuyama

AbstractBa1-xSrxTiO3 thin films have been deposited on Pt/Ti/SiO2/Si substra by the pulsed ArF laser deposition method. Deposition conditions, such as ambient gas and substrt temperatze, have been optmized to rrxove crystallinepropesty. Fe oelectric p e phasehasbeenobtainod ithe BSTthin filns deposited above 500°C in Q2 gas havingpressure ofabout 13Pa. Using N2O gas instead of O2 gas improved the crystallinity, because highly chemical active oxygen radicals produced due to ultraviolet inadiation of the laser. Doping of Bi ranging around 2% fills of the role of decrease leakage current of BST thin films. Temperature dependence of the dielectric constant (εr) shows a sharp change, peaking aroumd room temperature. The peak point exists below 25°C in the ratio of Ba/Sr=1.1 film, and shills above 50°C in Ba/Sr=5.7 film. When the Ba/Sr ratio is 1.4 the dielectric peak exists near 27°C and is very sharp. The maxinium differentW rate of dielectric constanttversus temperature is the largest in Ba/Sr=1.4 film and is about 100K-1. This value is equivalent to apyroelectric coefficient of 1.8 × 10-7 C/cm2K, which is almost the same as that of LiTaO3 single crystl, a typical pyroelectric material.


2002 ◽  
Vol 91 (10) ◽  
pp. 8093 ◽  
Author(s):  
Wan Kyu Park ◽  
Ricardo J. Ortega-Hertogs ◽  
Jagadeesh S. Moodera ◽  
Alex Punnoose ◽  
M. S. Seehra

2009 ◽  
Vol 1199 ◽  
Author(s):  
Danilo G Barrionuevo ◽  
Surinder P Singh ◽  
Maharaj S. Tomar

AbstractWe synthesized BiFe1-xMnxO3 (BFMO) for various compositions by sol gel process and thin films were deposited by spin coating on platinum Pt/Ti/SiO2/Si substrates. X-ray diffraction shows all the diffraction planes corresponding to rhombohedrally distorted perovskite BiFeO3 structure. The absence of any impurity phase in the films suggests the incorporation Mn ion preferentially to Fe site in the structure for low concentration. Magnetic measurements reveal the formation of ferromagnetic phase at room temperature with increased Mn substitution. On the other hand, ferroelectric polarization decreases with increasing Mn ion concentration. Raman studies suggest the dopant induced structural distortion.


Sign in / Sign up

Export Citation Format

Share Document