Structure, microstructure, and giant magnetoresistance in nanogranular FeAgNi thin films

Structural, microstructural, and magnetoresistive properties of metallic Fe(x)Ag(y)Ni(z) granular thin films were studied. These films with several compositions were prepared by dc magnetron sputtering. X-ray diffraction (XRD) measurements carried out on the samples show only Ag(111) peaks. The d-spacings determined from the Ag(111) peaks are smaller than the standard value for bulk Ag indicating a partial intermixing of Fe and Ni atoms in Ag. The diffraction pattern obtained using Transmission electron microscope (TEM) shows a number of Ag rings. Both XRD and TEM studies did not reveal any diffraction peaks due to Fe or Ni. The average particle size determined from the TEM micrograph is 5.5 nm whereas that determined from the XRD patterns is always higher. The magnetoresistance ratio for all the samples lies in the range 3 to 4.3%, except for a sample.     

Structure and magnetic properties of nanostructured Pd-Fe thin films produced by pulse electrodeposition

Nanostructured Pd-Fe thin films with varied Fe content were prepared by electrodeposition technique from organic electrolytes on Cu and brass substrates. The structure and the magnetic properties of the films were investigated prior to post-deposition annealing. The structure of the Pd1-xFe(x) thin film with x = 0.14, 0.24, and 0.52 was determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) as a solid solution of iron in palladium face-centered cubic lattice with the (111) orientation of nanograins relatively to the substrate surface. The films with higher iron concentration, x = 0.74, 0.91, have structure of a solid solution based on the body-centered cubic lattice. The average grain size determined by the scanning electron microscopy (SEM) for the first two alloys is 7-10 nm, and for the latter ones it is about 120 nm. The saturation magnetization of the films has linear dependence on the iron content, but coercivity has non-monotonic dependence on x, i.e., the films with x = 0.68 show highest coercivity. The magnetic anisotropy of the samples is studied by ferromagnetic resonance (FMR) spectroscopy.     

Influence of deposition potential on the electrodeposited Ternary CoFeCu films

Ternary CoFeCu films, relating their magnetic and magnetoresistance properties with film composition, surface morphology and the corresponding crystal structure, were investigated in terms of different deposition potentials in electrodeposition. The films were grown on polycrystalline titanium substrates. The potentials were obtained from cyclic voltammetry and the current–time transients were also recorded to control the growth of proper films. From the structural analysis by X-ray diffraction, all films had a face-centred cubic structure and the calculated grain size increased with increasing deposition potential. The film compositions by energy dispersive X-ray spectroscopy revealed that the Co, Fe and Cu contents varied and the scanning electron microscope images disclosed that the film morphologies changed as the deposition potential changed. The saturation magnetization was high and coercivity was low at high deposition potential. The easy axis of magnetization was parallel to the film plane for all films. All films showed anisotropic magnetic resistance and their magnitudes were between 3.2 and 3.8 %. The variations in magnetic and magnetoresistive properties related to the microstructure were attributed to the variation of the film contents caused by deposition potential.     

Deposition potential dependence of composition, microstructure, and surface morphology of electrodeposited Ni–Cu alloy films

Composition, microstructure, and surface morphology of Ni–Cu alloy films electrodeposited at different deposition potentials have been investigated. The microstructural analysis carried out by using X-ray diffraction (XRD) confirmed that all Ni–Cu films are polycrystalline in nature and possess face-centered cubic structure. XRD analysis also revealed that the (111) peak of the Ni–Cu alloy films splits into two as Cu-rich and Ni-rich peaks and the peak intensities change depending on the deposition potential and hence the film composition. Compositional analysis of Ni–Cu films carried out by energy dispersive X-ray spectroscopy showed that Ni content within the films increases as the deposition potential becomes more negative. The morphological analysis performed by using a scanning electron microscopy and an atomic force microscopy revealed that the surface morphology changes significantly with applied deposition potential. Furthermore, a direct correlation is observed between the surface roughness and lattice strain.     

Reactive DC Magnetron Sputtering Deposition of Copper Nitride Thin Film

Copper nitride thin film was deposited on glass substrates by reactive DC （direct current） magnetron sputtering at a 0.5 Pa N2 partial pressure and different substrate temperatures. The as-prepared film, characterized with X-Ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy measurements, showed a composed structure of Cu3N crystallites with anti-ReO3 structure and a slight oxidation of the resulted film.The crystal structure and growth rate of Cu3N films were affected strongly by substrate temperature. The preferred crystalline orientation of Cu3N films were （111） and （200） at RT, 100℃. These peaks decayed at 200℃ and 300℃ only Cu （111） peak was noticed. Growth of Cu3N films at 100℃ is the optimum substrate temperature for producing high-quality （111） Cu3N films. The deposition rate of Cu3N films estimated to be in range of 18-30 nm/min increased while the resistivity and the microhardness of Cu3N films decreased when the temperature of glass substrate increased.     

Microstructural and morphological characterizations of nanocrystalline Ni–Cu–Fe thin films electrodeposited from electrolytes with different Fe ion concentrations

In the current study, ternary Ni–Cu–Fe thin films have been grown from the electrolytes with different Fe ion concentrations onto indium tin oxide coated glass substrates by galvanostatic electrodeposition at ambient temperature. The microstructural, compositional, and morphological properties have been characterized with respect to Fe ion concentration using X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). EDX results indicated that the Fe content within the films increased and Ni and Cu contents decreased as the Fe ion concentration in the electrolyte was increased. From the XRD analysis, it was observed that the films have two separate, Cu-rich and Ni-rich phases. It was also observed that the phase separation becomes weaker with increasing Fe ion concentration. All of the films have face-centered cubic structure and [111] preferred crystallographic orientation. The texture degree of the Ni-rich (111) phase increased with the Fe ion concentration. SEM and AFM measurements revealed that the surface morphology is considerably affected by the Fe ion concentration. The size of the grains formed on the film surface and the surface roughness decreased as the Fe ion concentration within the electrolyte increased.     

Effects of molybdenum, silver dopants and a titanium substrate layer on copper film metallization

Annealing of 100 nm-thick Cu, Cu(Mo) and Cu(Ag) films was carried out to investigate the effect of dopant atoms on the films. Molybdenum (Mo) and silver (Ag) were selected as immiscible dopants for out-diffusion studies. A thermally grown SiO₂ layer and a sputtered Ti layer were used as substrates. The dopant and substrate effects were characterized in terms of surface morphology, resistivity, preferred orientation, and diffusional characteristics. The lowest observed resistivity was 2.32 · cm in the Cu(Ag) film, which was lower than that in a pure Cu film of the same thickness. Ag addition enhanced the surface morphology and thermal stability of the Cu(Ag) films. The highest thermal stability was obtained in the case of a Cu(Mo)/Ti film which maintained film integrity to 800°C. A Ti substrate enhanced Cu(111) texture growth. A highly oriented Cu(111)-texture was obtained in the Cu(Mo)/Ti films. Cu diffusion through the Ti layer was limited in the (111)-textured Cu(Mo)/Ti films, which showed good potential as a diffusion barrier.     

Surface Morphology, Structural and Magnetic Properties of Electrodeposited NiFeCu/Cu Films

The magnetic and structural properties of the NiFeCu/Cu films electrodeposited on polycrystalline titanium (Ti) substrates and their characterizations were studied. The structural analysis by X-ray diffraction (XRD) has revealed that all films have face-centred cubic (FCC) structure. On the other hand, the XRD analysis showed that the degree of (111) texture is dependent on the Cu content within the film. The composition analysis was carried out by energy-dispersive X-ray spectroscopy (EDX). The result of EDX indicated that the Cu content within the film increases with increasing of non-magnetic Cu layer thickness. The hysteresis loops of the films measured by vibrating sample magnetometer (VSM) showed that all films have a small coercivity typical for soft magnetic materials. The surface morphological structure of the films was investigated by atomic force microscopy (AFM). AFM images indicated that all films have main grains (globular islands) and smaller secondary grains on the main grains with different sizes. The differences observed in the magnetic properties of the films were attributed to the Cu content within the films.     

溅射SmCo基永磁薄膜的结构和磁性能研究

以Sm(Co0.62Fe0.25Cu0.1Zr0.03)7.5合金为靶材,采用磁控溅射工艺在单晶Si基片上沉积了SmCo基永磁薄膜。研究了溅射工艺参数对薄膜的晶体结构、微观结构和磁性能的影响。结果表明:溅射气压和溅射功率的改变引起了永磁相变,这主要依赖于溅射工艺条件对薄膜Sm含量的影响。高的溅射压强和溅射功率都会引起薄膜晶粒的粗大化和薄膜表面的粗糙化。薄膜的晶体结构和微观结构随溅射参数的变化决定了薄膜的面内磁学行为。当溅射压强为0.3 Pa和溅射功率为5.1 W/cm2时,制备的退火态SmCo基薄膜为TbCu7单相晶体结构,其面内永磁性能良好。     

Deposition of gold nanoparticles on electrospun MgTiO3 ceramic nanofibers

A simple method to deposit spherical gold nanoparticles on the surface of MgTiO3 ceramic nanofibers is presented. Electrospun MgTiO3/poly(vinyl acetate) (PVAc) hybrid nanofibers were calcined at 650 degrees C to obtain phase pure ceramic MgTiO3 nanofibers with 100-150 nm diameters. These ceramic nanofibers were immersed in an aqueous solution of HAuCl4 containing poly(vinyl alcohol) (PVA) as capping agent followed by photoreduction at 365 nm to get a novel Au-MgTiO3 nanocomposite. The formation of gold nanoparticles upon irradiation was confirmed by the appearance of a surface plasmon band (SPB) at 590 nm in the UV-visible absorption spectra. The surface morphology and elemental compositions were analyzed by the scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX), and transmission electron microscope (TEM). X-ray diffraction (XRD) and selected area diffraction (SAED) pattern in TEM revealed the crystallization of gold by exhibiting strong diffractions correspond to Au(111) and Au(200) crystalline planes in addition to the MgTiO3 diffraction.     

Ag-MgF2金属陶瓷薄膜的制备及其微观结构研究

用真空双蒸发源交替蒸发法和单蒸发源混合瞬时蒸发法制备了Ag-MgF2金属陶瓷薄膜。透射电镜、电子衍射、X射线衍射以及X射线光电子能谱分析结果表明，薄膜由晶态超微粒Ag镶嵌于主要为非晶态的MgF2中构成。Ag-MgF2形成的金属陶瓷复合晶体结构所对应的主要谱峰为d=0．26102，0．23540，0．20393nm。用真空单蒸发源混合瞬时蒸发法制备的Ag-MgF2薄膜表面元素的结合能大于双蒸发源交替蒸发法制备的薄膜表面元素的结合能。     

Ag~+/TiO_2-ZnO纳米复合薄膜的制备及双亲性能

采用溶胶-凝胶法制备了TiO2薄膜、TiO2-ZnO纳米薄膜和Ag+/TiO2-ZnO纳米薄膜。通过X射线衍射和原子力显微镜表征了样品的晶相、晶粒尺寸和形貌。以水(H2O)作为极性溶液参照物、苯(C6H6)作为非极性溶液参照物,研究了掺杂量、煅烧温度、表面处理对薄膜光致双亲性的影响。结果表明:在ZnO/TiO2复合薄膜中,适量掺杂Ag+会提高其双亲性,摩尔比为1%时最佳。煅烧温度的不同能够导致薄膜的晶粒粒径、晶型及薄膜表面的粗糙度发生变化,从而影响薄膜的双亲性能。煅烧温度为550℃、经酸溶液或热处理后Ag+/TiO2-ZnO纳米薄膜的双亲性最佳,其晶粒粒径约为21.1nm。此时,亲水角和亲油角分别为2°和0.5°。Ag+/TiO2-ZnO纳米薄膜的双亲性明显高于纯TiO2和TiO2-ZnO纳米薄膜。     

(Cu,Fe, Co,or Ni)-doped tin dioxide films deposited by spray pyrolysis: Doping influence on thermal stability of the film structure

The results of doping influence on thermal stability of the SnO₂ film morphology are presented in this article. The SnO₂ films doped by Fe, Cu, Ni, Co (16 at.%) were deposited by spray pyrolysis from 0.2 M SnCl₄–water solution at T_pyr 350–450 °C. The annealing at 850–1030 °C was carried out in the atmosphere of the air. The change of such parameters as film morphology, the grain size, texture and the intensity of X-ray diffraction (XRD) peaks have been controlled. For structural analysis of tested films we have been using X-ray diffraction, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM) techniques. It was established that the doping does not improve thermal stability of both film morphology and the grain size. It was made a conclusion that the increased contents of the fine dispersion phase of tin oxide in the doped metal oxide films, and the coalescence of this phase during thermal treatment are the main factors, responsible for observed changes in the morphology of the doped SnO₂ films.     

Properties of electrodeposited Fe–Cu films grown on ITO coated glass substrates at different electrolyte temperatures

In this study, effect of electrolyte temperature on structural and morphological properties of Fe–Cu films electrodeposited on ITO coated glass substrates has been investigated. Structural analysis carried out by using X-ray diffraction indicated that the films consist of a mixture of face-centered cubic (FCC) Cu and body centered cubic (BCC) α-Fe phases. It was found that the crystalline size of both Fe and Cu increases with increasing electrolyte temperature. Compositional analysis performed using energy dispersive X-ray spectroscopy showed that the Cu content within the films enhances with increasing electrolyte temperature. The surface morphology of Fe–Cu films was studied using a scanning electron microscopy (SEM). SEM results indicated that the surface morphology of Fe–Cu films significantly depends on the electrolyte temperature. The investigation of the residual stress in the films indicated that the residual stress for the FCC Cu is tensile in all films regardless of electrolyte temperature, whereas, for the BCC Fe, it depends on the electrolyte temperature. Correlation between the surface morphology and the residual stress is discussed in terms of the obtained results.     

Effect of internal strain on magnetic properties of La0.7Sr0.3MnO3 films

Oriented La_0.7Sr_0.3MnO₃ (LSMO) films were grown on (100) LaAlO₃ (LAO) and SrTiO₃ (STO) substrates by the method of radio frequency magnetron sputtering. X-ray diffraction patterns of LSMO films deposited on LAO and STO substrates showed a slight shift of diffraction peaks as compared to the corresponding peaks of the bulk LSMO. The shift of diffraction peaks was believed to result from the in-plane lattice mismatch between the film and substrate. The distinguished strain effects of substrates were found to be effective on the magnetic properties and the surface morphology of LSMO films on both substrates. The results indicate that STO substrate may be the promising candidate for room-temperature applications of LSMO film.     

Effect of doping on properties of Zno:Cu and Zno:Ag thin films

ZnO:Cu and ZnS thin films were grown by metal-organic chemical vapour deposition (MOCVD) under atmospheric pressure onto glass substrates. The ZnO:Ag films were fabricated from ZnS films by non-vacuum method that consists of simultaneous oxidation and Ag-doping by the close spaced evaporation (CSE) of silver at the temperature of 500–600 °C. Photo-assisted rapid thermal annealing (PARTA) at ambient air during 10–30 s at the temperature of 700–800 °C was used for the ZnO:Cu films. The samples were studied by X-ray diffraction technique (XRD), atomic force microscopy (AFM), and photoluminescence (PL) measurements. The grain size of ZnO:Cu films increased with an increase of Cu concentration. PL spectra of as-deposited ZnO:Cu films depended on Cu concentration and contained the bands typical for the copper. After PARTA at high temperature the emission maximum shifted towards the short-wave region. During the fabrication of ZnO:Ag films the grain growth process was strongly affected by the Ag loading level. The grain size increased with an increase of Ag concentration and ZnO:Ag films with surface roughness of 8 nm were obtained. Observed 385 nm PL peak for these samples can be attributed to the exciton–exciton emission that proves the high quality of the obtained ZnO:Ag films.     

Crystal orientation changes of Ag thin films on the Si(111) substrate due to tribo-assisted recrystallization

Crystal orientation changes of Ag thin films due to the tribo-assisted recrystallization have been studied using grazing incidence X-ray diffraction with synchrotron radiation. After preparation of an Si(111) √3 × √3-Ag surface, a 5-nm-thick Ag film was deposited on the surface at the substrate temperature of 303 K in an ultra-high vacuum chamber. The friction experiments were carried out using a diamond pin-on-plate type tribometer just after the Ag deposition in the same UHV chamber. We found that the coefficient of friction of the Ag films on the Si(111) √3 × √3-Ag surface decreases from 0.07 to 0.03, with increasing reciprocal sliding cycles. In synchronization with the coefficient change, Ag{100} grains are gradually disappearing. As a result, the Ag{111} grains cover the entire surface after 50 sliding cycles. Moreover, we found that the domain size of the Ag{111} grains increases with increasing reciprocal sliding cycles by measuring the rocking curve width. These results directly show that the Ag(111) plane is the sliding plane of friction and the coefficient of friction of Ag films is determined by the fraction of the Ag(111) grains in the Ag films. Moreover, to clarify the reaction between the Ag film and the Si substrate due to the tribo-assisted recrystallization, the substrate strain has been studied by an extremely asymmetric X-ray diffraction technique using synchrotron radiation.     

扩散阻挡层对Cu-Zr合金膜表面形貌与结构的影响

用磁控溅射和离子束溅射共沉积的方法，分别以TiN,TaN,ZrN为扩散阻挡层，在单晶硅片上制备了Cu-Zr合金膜，膜在400℃氮气中退火1h，研究表明，不同扩散阻挡层上Cu-Zr膜的形貌不同，沉积态膜的组成颗粒以ZrN为扩散阻挡层的最小，退火后膜的颗粒长大，且Zr向膜表面和界面处扩散，沉积态的膜具有强的（111）取向，峰形宽化明显，退火后又出现（200）、（220）、（311）衍射峰，扩散阻挡层不同时Cu-Zr合金膜的（200）与（111）的强度比值不同。     

Growth of different shape Cu2O micro structures using PEDOT coated ITO electrode

Crystalline cuprous oxide (Cu2O) particles were successfully deposited on poly(3,4-ethylenedioxythiophene) [PEDOT] coated indium tin oxide (ITO) glass. PEDOT film was first prepared on ITO glass by electrochemical polymerization. Crystalline Cu2O particles were then deposited on the PEDOT film by applying various electrochemical synthesis methods using a copper sulfate precursor. The effects of applied electrochemical methods on the compositions, grain sizes and shapes, and surface morphologies of the electrodeposited films were investigated. The micro structures of Cu2O particles were confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). When the cyclic voltammetry (CV) and chronoamperometry (CA) were applied, fine Cu2O particles of cubic and pyramidal phase were formed, respectively. However, bare ITO electrode was used, metallic copper particle was obtained. It shall be assumed that PEDOT might act as a buffer layer in electrochemical reduction of cuprous ion. The details of PEDOT behavior will be the topic of future studies.     

超薄Ni81Fe19薄膜的各向异性磁电阻及磁性能

利用磁控溅射方法制备了一系列超薄Ta(5nm)/Ni81Fe19(20nm)/Ta(3nm)磁性薄膜。着重研究了基片温度、缓冲层厚度对Ni81Fe19薄膜各相异性磁电阻(AMR)及磁性能的影响。利用X射线衍射仪分析了薄膜结构、晶粒取向;用四探针技术测量了薄膜的电阻率和各向异性磁电阻;用FD-SMOKE-A表面磁光克尔效应试验系统测量了薄膜的磁滞回线。结果表明:在基片温度为400℃时制备的Ni81Fe19薄膜具有较大的各向异性磁电阻效应和较低的磁化饱和场,薄膜最大各向异性磁电阻为3.5%,最低磁化饱和场为739.67A/m。基片温度为500℃制备的薄膜,饱和磁化强度Ms值最大。随着缓冲层厚度x的增加,坡莫合金薄膜的AMR值先变大后减小,在x=5nm时达到最大值。