Rotation Speed-Induced Uniaxial In-Plane Anisotropy in Thin Films Deposited Onto a Rotating Substrate

The Rotating Cryostat system consists of a rapidly rotating, liquid-nitrogen-cooled drum, around which a substrate can be placed. The possibility of using multiport sources gives the system wide capabilities for producing new materials. The effects of various rotation speeds of 1900, 1500, 1000, 500, and 0 rpm on the magnetic properties of thin iron films deposited on different (glass, silicon, and Kapton) substrates from a resistively heated evaporation source and a dc sputtering source have been investigated. Magnetic measurement showed that the films have an in-plane magnetic anisotropy for all films deposited at high speeds on all types of substrates and the degree of magnetic anisotropy decreased with decreasing rotational speed for flexible Kapton substrate. While the glass and silicon substrates was stationary, in-plane magnetic anisotropy of the films dropped down to zero. The films deposited on Kapton showed the rotational-speed-dependent magnetic properties. Estimation of magnetic anisotropy confirms in-plane anisotropy in the films. Furthermore, as expected for all iron films no magnetic anisotropy perpendicular to film plane was observed irrespective of rotation speed and type of substrate used.     

Studies of the Vortex Related Phase Transition in YBCO Thin Films with Strong In-Plane Anisotropy

We have studied the vortex-related phase transition in a number of YBCO thin films that have in-plane anisotropy due to the c-axis lying at an angle to the substrate normal. The critical parameters T _t , z, and have been extracted from the scaling of dc I-V measurements made along the two principal transport directions in magnetic fields up to 1 tesla. The dependence of T _t upon the direction of the transport current in some classes of film and the very high z values cast doubt upon the established interpretation based simply upon a vortex liquid–vortex glass phase transition.     

Quantum Theory of Spin Wave Gap in Ultrathin Magnetic Films

A simple quantum model is presented for the spin wave energy gap in single-layer and thin magnetic films that include both the magnetic out-of-plane and in-plane anisotropies. The films are assumed to be under the influence of the out-of-plane direction of the applied magnetic field at zero temperature. The calculated equations present a nonzero spin wave gap at zero magnetic field which is strongly affected by anisotropies. The effects of the film thickness and the role of the applied field are also examined. We discuss the results in connection with experimental data reported for nanocrystalline amorphous CoFeB films with growth-induced anisotropy.     

Experimental Determination of the Nonuniform Shape-Induced Anisotropy Field in Thin Ni–Fe Films

We have determined the nonuniform distribution of the shape-induced magnetic anisotropy field for patterned thin films of Ni-Fe. To do this, we used integrated microstrip structures with different widths on identically patterned Ni-Fe cores to act as probes of the internal magnetic field. We verified the accuracy of the field profiles by comparing them with M-H loop measurements of the magnetic films     

氧化镍溶胶-凝胶薄膜阻变特性研究

用溶胶-凝胶法在1TO基片上旋涂制备了NiO薄膜,通过对ITO/NiO薄膜/GaIn器件进行伏安特性测试,研究了溶胶浓度、退火、层数以及Cu掺杂等对其电学特性的影响.结果表明:所制备NiO薄膜具有良好可重复双极电阻开关特性.其中,2％Cu掺杂0.2 mol/L溶胶、双层、400℃退火1h制备的薄膜,阈值电压较低,约0.8 V;而开关比受以上因素影响不明显,约3× 102.分析发现薄膜高阻态的荷电输运符合空间电荷限制导电机制,而低阻态为欧姆特性,阻变开关机理为阈值电场及焦耳热导致的氧空位细丝的形成与断裂.     

Structure and Magnetic Properties of BaCoTiFe10O19 Thin Films with an Easy-Axis In-Plane Orientation

BaCoTiFe10O19 hexaferrite thin films with an easy-axis in-plane orientation were prepared by crystallization of amorphous films deposited by rf magnetron sputtering. The structure and magnetic properties were investigated. It is shown that CoTi-doping leads to a reduction of spontaneous magnetization and magnetic moment, which is caused by non-collinear magnetic structure and surface spin canting of small particles. The substitution of CoTi for Fe can adjust coercivity and Curie temperature over a very wide range, while still maintaining the room temperature magnetization. It is found that BaCoTiFe10O19 films exhibit a large squareness of hysteresis loop, Sq = 0.68. Thus, this film is desirable for high-density longitudinal recording systems.     

The In-Plane Anisotropy of the Hall Anomaly in BSCCO Whiskers

No Heading The Hall effect in single crystal BSCCO whiskers has been measured, with the current flowing along the a and b crystallographic directions. The ab-plane anisotropy of the Hall anomaly is found. The magnitude of the anomaly, as well as its anisotropy, are strongly affected by the structural defects.PACS Numbers: 74.72.Hs, 74.80.Dm, 72.15.Gd.     

Magnetic Studies of Spin Wave in Fe/Ag Multilayer Films

Magnetic properties of Fe/Ag multilayer films are investigated and examined versus Fe layer thickness t _Fe. As a result, spontaneous magnetization M(T) temperature dependence has been revealed to be well described by a T ^3/2 law in all multilayer films (7 ?≤t _Fe≤60 ?). Spin-wave theory based on anisotropic ferromagnetic system has been also used to explain magnetization temperature dependence. For Fe layer thickness, approximate values for J ₀ bulk exchange interaction and J _s surface exchange interaction have been estimated. First principle calculations based on density functional theory (DFT) and Korringa–Kohn–Rostoker (KKR)—coherent potential approximation (CPA) method—combined with Local Spin Density Approximation (LSDA), are performed as well. Magnetic moment, in fcc Ag_1−x Fe _x and bcc Fe_1−x Ag _x systems, versus x is presented and discussed in terms of Fe content on magnetic coupling. Reasonable agreement between experimental data and theoretical calculations is highlighted.     

甩胶喷雾热分解法制备ITO薄膜及光电性能研究

按In:Sn(物质的量比)=9:1,InCl3·4H2O和SnCl4·5H2O为前驱物,采用自制甩胶喷雾热分解制备薄膜装置在普通玻璃衬底上沉积了ITO薄膜,结果表明,采用自制甩胶喷雾热分解制备薄膜新装置成功制备出ITO薄膜。该装置结构简单、操作方便。制备ITO薄膜优化条件为:甩胶转速800r/min、衬底温度250℃、退火温度450℃、载气为空气、流量为7L/min、液体雾化速度0.2ml/min、雾粒速度3.5m/s。薄膜的沉积时间为5min,薄膜厚度约1000nm,最低电阻率为0.75*10-4Ω·cm,薄膜在可见光范围(波长在400-700nm)内平均透光率为87.2%。衬底温度在200℃以上时呈现立方相结构。     

导波光学技术在测量“夹心”光学薄膜各向异性方面的应用:不同膜堆结构中同类薄膜特性的比较

本文介绍了应用导波光学技术测量“夹心”光学薄膜的特征参数的方法,并研究了比较简单的结构(由二、三层膜组成),检测到了高折射率薄膜的各向异性。从不同结构的膜系中的同类薄膜的比较中发现了单层膜与膜堆中对应的“夹心”膜之间在折射率和各向异性上的差别。     

Field Effects in Thin Films of Manganites Using a Planar Field Effect Configuration

Modulation of the metal-insulator phase transition of perovskite manganite oxides is achieved by a static electric field. The field is applied using a planar field-effect configuration, which was formed on a monolayer film. In such a field-effect configuration, La_1−x A _x MnO₃ film is used as the channel and substrate acts as the gate. Both divalence-doped (La_0.7Ba_0.3MnO₃, Pr_0.7Sr_0.3MnO₃), and tetravalence-doped (La_0.7Ce_0.3MnO₃) systems demonstrate significant field effects. The field modulations are found being nonlinear and polarity dependent on the applied bias. The results obtained in La_0.7Ce_0.3MnO₃ indicates that electron doped manganites have similar features as those found in hole doped manganites. The observed field effects were discussed with the percolative phase separation picture.     

Tunable Wave Propagation in Superconducting Microstrip Line Based on Ferroelectric Thin Films

The microwave propagation characteristics in superconducting microstrip line supported by ferroelectric layer are theoretically investigated. The control of propagation constant and attenuation coefficient of the waveguide with biasing electric field is analyzed using the spectral domain method. The dependence of propagation characteristics on thickness of ferroelectric thin film as well as operating frequency for different applied electric fields is studied. The variation of propagation constant with temperature is also investigated. This method of analysis can be easily implemented in the design of tunable microwave devices.     

Synthesis and Characterization of Indium Niobium Oxide Thin Films via Sol--Gel Spin Coating Method

In the present study, niobium-doped indium oxide thin films were prepared by sol-gel spin coating technique. The effects of different Nb-doping contents on structural, morphological, optical, and electrical properties of the films were characterized by means of X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, atomic force microscopy （AFM）, UV-Vis spectroscopy, and four point probe methods. XRD analysis confirmed the formation of cubic bixbyite structure of In203 with a small shift in major peak position toward lower angles with addition of Nb. FESEM micrographs show that grain size decreased with increasing the Nb-doping content. Optical and electrical studies revealed that optimum opto-electronic properties, including minimum electrical resistivity of 119.4 × 10^-3 Ω cm and an average optical transmittance of 85% in the visible region with a band gap of 3.37 eV were achieved for the films doped with Nb-doping content of 3 at.%. AFM studies show that addition of Nb at optimum content leads to the formation of compact films with smooth surface and less average roughness compared with the prepared ln2O3 films.     

Superconductivity, Spin Density Wave and Field Induced Spin Density Wave versus anion ordering in the (TMTSF)2ClO4 salt

An effect of electron correlation is studied in an angular dependence of magnetoconductivity of quasi one-dimensional organic conductors. We investigate the effect of both quasi-particle’s lifetime and velocity due to the electron correlation near SDW in the magnetoconductivity. We found that the momentum dependence of lifetime strongly suppresses the one-dimensional axis magnetoconductivity at a magic angle θ=45°. On the other hand, the change of the momentum dependence of the velocity originating from the electron correlation enhances the interchain magnetoconductivity at θ=0°. These effects are explained from the momentum dependence of lifetime and velocity over the electron’s commensurate orbital on Fermi surface at the magic angles.     

Analysis of the Anisotropy Field and the Saturation Magnetization for Ultrathin Ferromagnetic Films

We study the magnetic in-plane anisotropic fields for a two-dimensional film by including magnetic field in the basal plane for an easy axis film. We present the balance between the applied field and in-plane anisotropic field at equilibrium. We have also investigated the approach to saturation of magnetization and numerically solving the nonlinear equation for equilibrium, and results are discussed in connection with experimental data reported for Co films.     

Reentrant First-Order Transition of Superconductivity in Thin TiN Films Under the Spin Paramagnetic Limitation

Reentrant first-order transitions are observed in thin TiN films under the paramagnetic limitation of superconductivity when the tricritical point appears on the locus of the reentrant second-order transition.