Unusual field dependence of the Hall effect in Ni3Mn films

An anomalous behavior of the Hall emf E_h in disordered Ni₃Mn vacuum condensates is discovered. As the magnetic field H is increased from zero, E_h first increases in absolute value, its sign being negative. At a certain field, E_h then begins to decrease, passes through zero, and subsequently approaches saturation in the normal manner, its sign being positive. This behavior can be explained by assuming the presence in the condensate of several magnetic phases with emf values of different signs and with different saturation fields.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 101–104, December, 1976.     

The electrical properties of thin permalloy films

The magnetic properties of thin Permalloy films have been the subject of many investigations, but the work on their electrical properties is very limited [1]. By observing the change in electrical resistance with temperature the structural transformations taking place during the annealing of the condensates can be inferred.The authors of [1] did not undertake a detailed study of the electrical properties of Permalloy. They used Permalloy 79NMA in their investigation, and the dependence of the change in electrical resistance on the temperature of annealing in a magnetic field enabled them to reach conclusions about the nature of the uniaxial anisotropy of thin films.In the present work a detailed study has been made of the electrical resistance of Permalloy films in relation to the temperature of the substrate during evaporation and annealing; the temperature coefficient of resistance (TCR) has also been studied.     

Strain hardening and characteristics of the dislocation structure of the alloy Ni3Mn with a different order state

The strain hardening, dislocation structure, and shear localization in slip traces are studied in this paper, as a function of the state of order in a Ni₃Mn alloy. The existence of a correlation between the strain-hardening characteristics, the interdislocation parameter , the number of single dislocations, and the shear localization magnitude in slip traces is established in the alloy under investigation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 94–98, February, 1982.     

Reactively sputtered Ni, Ni(N) and Ni3N films: Structural, electrical and magnetic properties

Nickel thin films were deposited on glass substrates at different N₂ gas contents using a dc triode sputtering deposition system. Triode configuration was used to deposit nanostructured thin films with preferred orientation at lower gas pressure and at lower substrate temperature compared to the dc diode sputtering system. A gradual evolution in the composition of the films from Ni, Ni(N), to Ni₃N was found by X-ray diffraction analysis. The preferred growth orientation of the nanostructured Ni films changed from (1 1 1) to (1 0 0) for 9% N₂ at 100 °C. Ni₃N films were formed at 23% N₂ with a particle size of about 65 nm, while for 0% and 9% of nitrogen, the particles sizes were 60 nm, and 37 nm, respectively, as obtained by atomic force microscopy. Magnetic force microscopy imaging showed that the local magnetic structure changed from disordered stripe domains of about 200 nm for Ni and Ni(N) to a structure without a magnetic contrast, indicating the paramagnetic state of this material, which confirmed the structural transformation from Ni to Ni₃N.     

Thermoluminescent a-CN thin films properties as a function of plasma parameters

Amorphous carbon nitride (a-CN) thin films show luminescent properties that are of interest for many applications. Particularly interesting are their previously reported thermoluminescent characteristics. In order to optimize these properties, the plasma parameters (ion energy, plasma density and type of excited species) were studied in the present work as a function of the laser fluence and the working pressure. The plasma was produced using the fundamental line of a Nd:YAG laser with 28 ns pulse duration focused on a high purity graphite target. The laser fluences used in this work could be varied between 9 and 40 J/cm². Measurements and deposition of a-CN films were carried out in a nitrogen atmosphere at pressures from 3×10^-3 to 7.5×10^-2 Torr. We observed an optimum value of pressure, close to 7.5×10^-2 Torr, in which the nitrogen incorporation into the film achieved its maximum value close to 29 at.% and the thermoluminescent response of the material, after irradiation with UV becomes evident. PACS 81.15.Fg; 78.60.Kn; 81.05.Uw     

Magnetic properties of ultrathin Ni films

The magnetic properties of Au/Ni/Si(100) films with Ni thicknesses of 8–200 Å are studied at T=77 K using a scanning magnetic microscope with a thin-film high-temperature dc SQUID. It is found that the Ni films, with an area of 0.6×0.6 mm, which are thicker than 26 Å have a single-domain structure with the magnetic moment oriented in the plane of the film and a saturation magnetization close to 0.17 MA/m. For films less than 26 Å thick, the magnetization of the film is found to drop sharply.     

The electrical properties of evaporated films of cadmium sulphide

The electrical properties of vacuum evaporated layers of CdS on amorphous substrates have been investigated as a function of the various preparative parameters, i.e. evaporation rate, substrate temperature, thickness of the layers and purity of the source. The degree of preferential orientation of the crystallites which comprise the film has also been examined. It is shown that the resistivity of the films decreases with increasing thickness. This effect is associated with a corresponding increase in the density of free electrons, which it is suggested is associated with an increasing deviation from stoichiometry of the source as the evaporation proceeds. The variation of the Hall mobility with thickness can be explained in terms of surface scattering. A tentative model of the evaporation process is proposed which gives some insight into many of the experimental observations.     

Structurally sensitive magnetic and electrical properties of Fe15Co20Ni65 thin films

We have studied the influence of thickness, magnetic annealing temperature, and substrate material on a number of structurally sensitive magnetic and electrical properties of Fe₁₅Co₂₀Ni₆₅ films. It is shown that the main microstructure parameter which determines the resistivity, its temperature coefficient, the anisotropy of the magnetoresistivity, the coercive force, and the induced magnetic anisotropy field is the crystallite dimension d. We establish the conditions for producing a structural state (d=10 nm) which, from a practical standpoint, has an optimal relationship between the magnetic and magnetoresistance properties.Physics and Applied Mathematics Scientific-Research Institute, Urals State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 61–66, June, 1993.     

Pseudopotential calculation of the energy of vacancy formation in binary alloys as a function of the degree of far order

Pseudopotential theory is used to study the dependence of energy of vacancy formation E_IV ^f in binary replacement alloys as a function of the degree of far order is shown that E _IV ^f =E_o+E·]², where E_o is the energy of vacancy formation in a disordered alloy, E then contains the ordering energy. It is shown with examples of the alloys CuZn, AuZn, and AgCd that the energy of vacancy formation can decrease with increase in the degree of far order. It is found that in calculating the vacancy formation energy it is necessary to consider lattice relaxation energy, since such consideration can lead to a change in the sign of E.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 62–67, June, 1984.     

Electronic structure of the ordered ferromagnetic alloys Ni3Mn,Ni3Fe,and Ni3Co

Calculations of the band structure of the ferromagnetic alloys Ni₃Mn, Ni₃Fe, and Ni₃Co are presented. The results are compared with experimental data. Change in the electronic structure as one goes from Ni₃Mn to Ni₃Co is analyzed. The occurrence of ferromagnetism in the alloys studied and the possibility of their existence in an ordered ferromagnetic state are examined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 82–88, June, 1988.     

Effect of the state of long-range order and grain size on the work hardening of the alloy Ni3Mn

The dependence of the coefficients of the Petch equation = ₀ + + kd-1/2 on the degree of long-range order and deformation has been investigated. It is found that work hardening within a grain (d₀/d) is greater in the ordered state, while that at the grain boundaries (dk/d) is greater in the disordered state. The hardening coefficient at stage II, ®_II, is almost independent of the degree of ordering , and the stress at the beginning of stage III decreases considerably with reduction of . The nature of the maximum of the flow stress for the ordered alloy has been analyzed in detail for 0 < < 1. The contribution of certain mechanisms which may cause the appearance of this maximum to the flow stress has been estimated. It is concluded that a definitive solution of this problem is not possible at the present time.     

Surface properties of platinum thin films as a function of plasma treatment conditions

We examined the surface properties of platinum (Pt) thin films exposed to oxygen and argon plasma treatments and compared them to as-deposited Pt films. The surface wetting properties, refractive index and extinction coefficient of the Pt films were monitored as a function of time after different plasma treatments. Surfaces treated with an oxygen plasma were dramatically different from as-deposited Pt, whereas argon plasma treated surfaces were similar to as-deposited films. X-ray photoelectron spectroscopy confirmed the formation of platinum oxide on films treated with an oxygen plasma, while such oxide diminished after argon plasma treatment. Surface morphology studied with atomic force microscopy indicated a strong dependence of the surface roughness of the Pt films on the power and duration of the argon plasma used for the treatment. Based on these studies, an oxygen plasma treatment followed by a brief low-power argon plasma etch was developed for the purpose of regenerating clean and metallic Pt surfaces, and at the same time providing the smoothest possible surface morphology.     

The electrical properties of sulfur-implanted cubic boron nitride thin films

Cubic boron nitride (c-BN) thin films are deposited on p-type Si wafers using radio frequency (RF) sputtering and then doped by implanting S ions. The implantation energy of the ions is 19 keV, and the implantation dose is between 10 15 ions/cm 2 and 10 16 ions/cm 2 . The doped c-BN thin films are then annealed at a temperature between 400°C and 800 C. The results show that the surface resistivity of doped and annealed c-BN thin films is lowered by two to three orders, and the activation energy of c-BN thin films is 0.18 eV.     

Optical and electrical properties of tin-dioxide films

Summary The electro-optical properties of thin SnO₂ films are analysed in relation to different experimental deposition conditions. Heating tests have been performed on the samples; the results are discussed.

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Riassunto Si analizza l'influenza di differenti condizioni sperimentali di deposizione sulle proprietà elettro-ottiche di film sottili di SnO₂. Si riportano i risultati di prove di invecchiamento condotte mediante cicli termici.

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Резюме Анализируется влияние различных экслериментальных условий напыления на электрические и оптические свойства тонких пленок диоксида олова. Проводятся испытания с использованием темических циклов. Обосуждаются полученные резльтаты.

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This work has been performed in the framework of activities of the ?Progetto Finalizzato Energetica? supported by the C.N.R.