Magnetoresistive properties of Ni-based thick films (original) (raw)
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Hybrid thick-film magnetoresistive sensors
Sensors and Actuators A: Physical, 1992
This paper describes a first prototype of a thick-film sensor using Ni-based pastes, whose resistance changes with the applied magnetic field. The magnetoresistive properties of thick films (It&. Parent No. 9477/A86 (1986)) have been exploited for the development of hybrid sensors for proximity detection and rotational speed. The conditioning electronic circuits are specifically designed to compensate the relevant temperature effects, which otherwise would overwhelm the weak magnetoresistive effects. The electronic solution, though simple, proves to be very effective. On this basis integrated magnetoresistive sensors, with standard trimmable hybrid circuits and Ni-based films on the same substrate, have been developed in the framework of a collaboration aimed at looking for reliable integrated sensors for various applications. The design and operation of a prototype are described. Some areas of application of hybrid magnetoresistive sensors will be analysed.
Journal of Materials Science: Materials in Electronics, 2017
Electrodeposition of Ni-Fe soft magnetic alloy on copper and stainless steel substrates was performed in chloride bath. The deposition parameters such as current density, pH, temperature and deposition time have been investigated. From the investigation the optimized deposition parameters were current density 3.5 mA/cm 2 , pH 3, temperature 30 °C and deposition time 15 min. The Ni-Fe magnetic alloys deposited on copper and stainless steel substrates under optimized deposition parameters are subjected to various characterizations. The structural and surface morphology of the Ni-Fe films were detected by using X-ray diffractogram (XRD) and scanning electron microscope (SEM) respectively. The constituents in the films were determined by energy dispersive X-ray spectroscopy (EDAX) technique. The magnetic properties such as the coercivity (H c) and saturation magnetization of the films were studied with the help of vibrating sample magnetometer (VSM). From the magnetic studies it is concluded that the grain size are create a considerable impact on magnetic behavior of the films on both the substrates. The films prepared on stainless steel substrate of 0.1 M concentration at optimized deposition parameters exhibits higher coercivity (5010 Oe) which seems to be ideal for magnetic sensor applications.
2015
Nickel thin films have been prepared by using electron beam evaporation technique at a pressure of 410 mbar on silicon and glass substrates. Some of as-deposited films have been annealed at 573 K for 1.5 hours in open air. Electrical and morphological properties of both as-deposited and annealed films are investigated. The magnetic properties of as-deposited Ni films are studied by VSM at room temperature. The resistivity of Ni films on silicon substrate is higher than resistivity of Ni films found on glass substrate. T.C.R. of Ni films is found to be positive indicating metallic nature of the samples. Coercivity of Ni films increases with the increase of film thickness. The coercivity of 80 nm as-deposited Ni film on glass substrate is 9 Oe. The rms value of surface roughness of 150 nm as-deposited Ni films on glass substrate is 12 nm. It becomes 7 nm after annealing. On the other hand the coercivity of 90 nm and 160 nm as-deposited Ni films on silicon substrate is 50 Oe and 85 Oe...
INVESTIGATION OF Ni-Cu THIN FILMS MAGNETIC SENSORS DEPOSITED ON SiO2 SUBSTRATES BY SPUTTERING
2019
The objective of this paper it is to produce magnetic sensors with thin Ni-Cu layers with GMR, sputtered on SiO2 substrate, which could be used as magnetic field sensors. Determination of the thickness and uniformity of the magnetic sensor layers it is done by optical microscopy and atomic force microscopy (AFM) for different areas. Finally, measurements were made using the MF100 AC/DC magnetometer and the experimental results were processed. As a magnetic field source, we used a ferrite ring magnet, Y35, with 6 kg force (about 58.8 N).
Journal of Superconductivity and Novel Magnetism, 2012
The surface morphology and magnetic properties of Co-Ni-N thin films electrodeposited under an external magnetic field were investigated. The films were electroplated on Al substrates using the same electrodeposition parameters (temperature and pH) for all experiments, with an external magnetic field of 107 Oe applied to the cathode surface. The films were compared with similar samples obtained in the absences of magnetic field. The magnetoinduced modifications in the Co-Ni-N morphology can be explained by the specific local convection of ions at the interface cathode-electrolyte, which promotes changes both in the electrical charge of the double layer and in the thickness of the diffusion layer. From the magnetic measurements, we found that the coercivity varied between H c = (14 ÷ 27) kA/m depending on the direction of the applied magnetic field and on the sodium nitrate content in the plating bath. It was observed that an induced anisotropy ap
Sensors and Actuators A: Physical, 2006
The effect of the various cathode potentials applied in continuous and pulse waveforms on magnetic anisotropy of NiFe alloy films grown on (1 0 0) textured polycrystalline copper substrates has been studied. Magnetic measurements obtained by a vibrating sample magnetometer (VSM) showed that the magnetic anisotropy of the films is very sensitive to the cathode potentials and the type of the potentials applied during deposition. It was found that the easy axis of all films is in the film plane. The magnetic findings also indicated that the NiFe films deposited at the cathode potentials of −1.2 and −1.5 V applied in the continuous waveforms, but except for the films deposited at the cathode potential of −1.8 V, are anisotropic, while those produced at the cathode potentials applied in the pulse waveform show an isotropic magnetic behaviour. Utilising the magnetic properties of the films may offer the potential for the development of a new range of stress sensors.
Characterization of magnetic iron and nickel vapor deposited films
Journal of Physics and Chemistry of Solids, 1999
We prepared several samples of pure Fe and Ni films, evaporated in high vacuum conditions onto Cu foils or mica, ranging in thickness between 50 and 300 nm and measured their magnetization near the critical point in a protective atmosphere. The value of the T c for the films thinner than 200 nm, grown on Cu, resulted lower than the respective bulk T c Further, for these films the magnetization decreases linearly with temperature near T c. Films of Ni grown on mica do not show a shift in T c relative to bulk Ni. The bulk saturation magnetization is obtained for Fe and Ni films grown onto mica at relative low fields (45 G) while on the films grown onto Cu more than 300 G are needed to obtain the bulk magnetization value. Characterization of the films with scanning electron and transmission microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and Auger depth profiling was performed. These analyses indicate that the films initially are of good quality but heating them up to the transition temperature promotes interdifussion of the films with the Cu substrate.
Preparation of nickel oxide thin films for gas sensors applications
Sensors and Actuators B: Chemical, 1999
In this paper, we present the results concerning the Pt surface modification of nickel oxide thin films deposited by dc reactive magnetron sputtering. Pt very thin overlayers with a thickness of about 3 and 5 nm have been sputtered on the top of NiO samples. The surface structure and morphology of the samples have been analysed by X-ray diffractometer (XRD) and by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The electrical responses of the NiO-based sensors towards different H 2 concentration (500-5000 ppm) have been also considered. The Pt-modified NiO samples showed an enhancement of the response towards H 2 as compared to the unmodified NiO sample. The thickness of the Pt thin layers seems also an important parameter in determining the properties of the NiO films as H 2 sensors.
Magnetic Behavior of [Ni/Co?Ni?Mg?N] � n Cylindrical Multilayers prepared by Magnetoelectrolysis
physica status solidi (a), 2002
Metallic multilayers comprising ferromagnetic layers with different coercivities are of interest for magnetic sensor applications. Our purpose is to analyze the effects of interlayer coupling and number of interfaces between layers on the magnetic behavior of [Ni/Co-Ni-Mg-N] Â n multilayers. The number n of periods varied from 1 to 52 for a total multilayer thickness of 1.5 mm. The multilayers were deposited onto a copper wire in an electrolytic cell system with a magnetic field H d externally imposed during electroplating. The magnetic susceptibility curves obtained by induction method using a digital scope interfaced to computer were analyzed by real-time Fast-Fourier-Transform (FFT) analysis. The magnetic behavior is explained by the complex internal magnetic configuration of the samples.