scholarly journals Structural and magnetic anisotropy of directionally-crystallized ferromagnetic microwires

2018 ◽  
Vol 185 ◽  
pp. 04022 ◽  
Author(s):  
Svetlana Evstigneeva ◽  
Alexander Morchenko ◽  
Alexey Trukhanov ◽  
Larissa Panina ◽  
Vladimir Larin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Amorphous State ◽  
Xrd Analysis ◽  
Anisotropy Axis ◽  
X Rays ◽  
Directional Crystallization ◽  
Wire Axis ◽  
The Face ◽  
The Wire ◽  
Face Centered

Amorphous ferromagnetic microwires have drawn attention primarily due to their excellent soft magnetic properties as the elements of sensors. In this work, semi-hard magnetic microwires of composition Fe4.3Co67.7Si11B14Cr3 were obtained after a process of directional crystallization from amorphous state. The XRD analysis of crushed and whole wires identified the formation of the face-centered Co-modification as the main phase of directionally crystallized core alloy, which explains a large increase in anisotropy and coercivity. The application of a magnetic field during crystallization may orient the easy anisotropy axis of crystallites along the wire. This is confirmed by the investigation of crystallite orientation with respect to the wire axis and X-rays direction in diffractometer. The obtained results revealed that the formation of crystallites in amorphous Co-rich microwires occurs with the predominant orientation of the crystallographic direction [111] along the wire axis and the direction of a magnetic field during the directional crystallization process.

Transport Properties of Topological Insulator Bi0.83Sb0.17 Nanowires

2015 ◽  
Vol 1785 ◽  
pp. 1-6
Author(s):  
L.A. Konopko ◽  
A.A. Nikolaeva ◽  
T.E. Huber ◽  
J.P. Ansermet
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Transport Properties ◽  
Topological Insulator ◽  
Energy Gap ◽  
Oscillation Amplitude ◽  
Glass Capillary ◽  
Wire Axis ◽  
Temperature Dependences ◽  
The Wire

ABSTRACTWe have investigated the transport properties of topological insulator based on single-crystal Bi0.83Sb0.17 nanowires. The single-crystal nanowire samples in the diameter range 200 nm – 1.1 μm were prepared by the high frequency liquid phase casting in a glass capillary using an improved Ulitovsky technique; they were cylindrical single-crystals with (1011) orientation along the wire axis. In this orientation, the wire axis makes an angle of 19.5o with the bisector axis C1 in the bisector-trigonal plane. Bi0.83Sb0.17 is a narrow gap semiconductor with energy gap at L point of Brillouin zone ΔE= 21 meV. In accordance with the measurements of the temperature dependence of the resistivity of the samples resistance increases with decreasing temperature, but at low temperatures decrease in the resistance is observed. This effect, decrease in the resistance, is a clear manifestation of the interesting properties of topological insulators - the presence on its surface of a highly conducting zone. The Arrhenius plot of resistance R in samples with diameter d=1.1 µm and d=200 nm indicates a thermal activation behavior with an activation gap ΔE= 21 and 35 meV, respectively, which proves the presence of the quantum size effect in these samples. We found that in the range of diameter 1100 nm - 200 nm when the diameter decreases the energy gap is growing as 1/d. We have investigated magnetoresistance of Bi0.83Sb0.17 nanowires at various magnetic field orientations. From the temperature dependences of Shubnikov de Haas oscillation amplitude for different orientation of magnetic field we have calculated the cyclotron mass mc and Dingle temperature TD for longitudinal and transverse (B||C3 and B||C2) directions of magnetic fields, which equal 1.96*10-2m0, 9.8 K, 8.5*10-3m0 , 9.4 K and 1.5*10-1m0 , 2.8 K respectively. The observed effects are discussed.

Microstructures and Magnetic Properties of CoPt-C Nanogranular Films

2017 ◽  
Vol 727 ◽  
pp. 985-990
Author(s):  
Lei Ma ◽  
Mu Fen He ◽  
Gang Cheng ◽  
Zheng Fei Gu
Keyword(s):  
Magnetic Properties ◽  
Annealing Temperature ◽  
Amorphous State ◽  
Nanocomposite Films ◽  
Face Centered Cubic ◽  
Doping Amount ◽  
Uniform Size ◽  
The Face ◽  
Face Centered ◽  
High Density Magnetic Recording

CoPt-C films were fabricated on silicon substrate by dc reactive magnetron sputtering followed by vacuum annealing. The effects of C additions and annealing temperature on the microstructure and magnetic properties were investigated. The as-deposited films had flat, compact surfaces and face-centered cubic structure, which transforms into the face-centered tetragonal structure after thermal annealing at 700°C for 1 hour. The grain size of CoPt increased with the annealing temperature but decreased with increasing C content. No carbide appearing, the C content exists in amorphous state in the nanocomposite films, and it is homogeneous distributed between the CoPt nanograins, which have the benefit to restrain grain growth and obtain isolated CoPt particles with uniform size. The fct-CoPt films annealed at 700°C exhibited high in-plane coercivity, up to 4200 Oe at room temperature and better square degrees. In the CoPt-C granular films, the best doping amount is about 35 at.% C. These CoPt-C films with novel embedded structure and moderate coercivity have shown promise for high density magnetic recording medium.

Angular dependence of giant magneto impedance and magnetic characteristic of Co-based wire in different magnetic field ranges

2014 ◽  
Vol 28 (25) ◽  
pp. 1450197 ◽  
Author(s):  
Reza Mardani ◽  
Ahmad Amirabadizadeh ◽  
Majid Ghanaatshoar
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Angular Dependence ◽  
Hysteresis Loops ◽  
Magnetic Characteristic ◽  
Field Range ◽  
Wire Axis ◽  
Amorphous Wires ◽  
Giant Magneto Impedance ◽  
The Wire

Angular dependence of the giant magneto impedance (GMI), hysteresis loops and magnetization curves have been investigated in amorphous wires with respect to direction and amplitude of the magnetic field in room temperature. The measurements were performed at different orientation angles of the applied magnetic field relative to the wire axis and various magnetic field strengths in moderate (0–200 Oe) and high (0–5000 Oe) ranges. The highest GMI response (500%) and magnetization (100 emu/gr) were found for angles close to the wire axis in high magnetic field range. By increasing the angle from 0°, in moderate external magnetic fields the GMI and magnetization decrease without reaching the saturation. However, in high magnetic fields (~ 5000 Oe) these parameters are nearly constant and almost saturated for all angles. In both magnetic field ranges, increasing the angle of applied field widens the impedance curves.

Evolution of the Transrotational Structure During Crystallization of Amorphous Ge2Sb2Te5 Thin Films

2009 ◽  
Vol 1160 ◽  
Author(s):  
Emanuele Rimini ◽  
Riccardo De Bastiani ◽  
Egidio Carria ◽  
Maria Grazia Grimaldi ◽  
Giuseppe Nicotra ◽  
...  
Keyword(s):  
Thin Films ◽  
Film Surface ◽  
Xrd Analysis ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
Tem Analysis ◽  
The Face ◽  
Face Centered ◽  
Average Lattice

AbstractThe crystallization of amorphous Ge2Sb2Te5 thin films has been studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The analysis has been performed on partially crystallized films, with a surface crystalline fraction (fS) ranging from 20% to 100%. XRD analysis indicates the presence, in the partially transformed layer, of grains with average lattice parameters higher than that of the equilibrium metastable cubic phase (from 6.06 Å at fS=20% to 6.01 Å at fS=100%). The amorphous to crystal transition, as shown by TEM analysis, occurs through the nucleation of face-centered-cubic crystal domains at the film surface. Local dimples appear in the crystallized areas, due to the higher atomic density of the crystal phase compared to the amorphous one. At the initial stage of the transformation, a fast bi-dimensional growth of such crystalline nucleus occurs by the generation of transrotational grains in which the lattice bending gives rise to an average lattice parameter significantly larger than that of the face-centered-cubic phase in good agreement with the XRD data. As the crystallized fraction increases above 80%, dimples and transrotational structures start to disappear and the lattice parameter approaches the bulk value.

Electroless Deposition of Silver Nanoparticles and Nanowires in Ethylene Glycol

2014 ◽  
Vol 1043 ◽  
pp. 109-113 ◽  
Author(s):  
Nathaniel de Guzman ◽  
Aurelia Mechilina ◽  
Mary Donnabelle Balela
Keyword(s):  
Molecular Weight ◽  
Ethylene Glycol ◽  
Ag Nanoparticles ◽  
Electroless Deposition ◽  
Xrd Analysis ◽  
Metallic Silver ◽  
Face Centered Cubic ◽  
Structure Directing Agent ◽  
The Face ◽  
Face Centered

Silver (Ag) nanostructures, such as nanoparticles and nanowires, were formed by electroless deposition in ethylene glycol at 160 °C for 1h. Polyvinyl pyrrolidone (PVP) were used both as a capping agent and structure-directing agent to prevent agglomeration and promote the growth of Ag nanowires. The effect of its molecular weight and concentration on the morphology of Ag was examined by X-Ray Diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis showed peaks corresponding to the face-centered cubic (FCC) structure of metallic silver. At low PVP molecular weight of 10,000, spherical Ag nanoparticles with a mean diameter of about 170 nm were formed. A mixture of Ag nanoparticles and nanowires were produced when the molecular weight was increased to 55,000 and 360,000.

Deformation Twins in Drawn Aluminum - 0.9% Magnesium Wire

1968 ◽  
Vol 26 ◽  
pp. 274-275
Author(s):  
S. C. Dexter ◽  
I. G. Greenfield
Keyword(s):  
Electron Microscopy ◽  
Fiber Texture ◽  
Mechanical Twinning ◽  
Face Centered Cubic ◽  
Wire Axis ◽  
Cubic Metals ◽  
Thin Foils ◽  
The Wire ◽  
Face Centered ◽  
Mechanical Twins

A number of mechanisms have been suggested for the formation of the duplex <111> + <100> fiber texture in drawn wires of face centered cubic metals. Ahlborn and Wassermann proposed that mechanical twinning and subsequent twin rotation are responsible for this type of texture. They theorize that during deformation a <111> direction in each grain becomes aligned parallel to the wire axis, and that mechanical twins form in this matrix with the <511> twin direction also parallel to the wire axis. Upon further deformation, the <100> twin direction which is about 19.5 degrees from the wire axis rotates and approaches the wire axis.Twins of this type and in a range of orientations corresponding to the rotation postulated were observed directly in drawn wires of Al - 0.9% Mg by transmission electron microscopy. The wires were cold drawn 96% to a final diameter of 0.038 inches. Longitudinal thin foils were prepared for electron microscopy in a two step process.

Stress in Spin Valve Multilayers During Antiferromagnetic Phase Transformation

1999 ◽  
Vol 594 ◽  
Author(s):  
B. J. Daniels ◽  
S. P. Bozeman ◽  
H HA
Keyword(s):  
Magnetic Field ◽  
Phase Transformation ◽  
Applied Magnetic Field ◽  
Spin Valve ◽  
Spin Valves ◽  
Face Centered Cubic ◽  
Antiferromagnetic Phase ◽  
Wafer Curvature ◽  
The Face ◽  
Face Centered

AbstractThe stresses in sputter-deposited, NiMn- and PtMn-pinned top spin valve multilayers were measured using a laser-based wafer curvature technique. As-deposited stresses were 150 to 180 MPa in compression for NiMn- and 970 to 1020 MPa in compression for PtMn-pinned spin valves. Following deposition and stress measurement, these films were annealed in an applied magnetic field of 250 Oe for 2 hours at 300°C. This anneal causes the antiferromagnetic layer to undergo a phase transformation from the face-centered cubic (fcc) to the face-centered tetragonal (fct) crystal structure. This phase transformation increases the average stresses in the spin valves to 740–800 MPa in tension for the NiMn-pinned spin valves and to 475–580 MPa for the PtMnpinned spin valves. Stress changes during the antiferromagnetic phase transformation were also observed as a function of annealing temperature and time during substrate heating, annealing, and cooling. The stress varied nearly linearly with temperature during the heating and cooling of the substrate, indicating that the bulk of the phase transformation occurs during the isothermal portion of the anneal. By monitoring stress vs time during the isothermal anneal, the progression of the antiferromagnetic phase transformation was observed. Final stress data obtained from the wafers annealed in the wafer curvature system (no applied magnetic field) are within 10% of those obtained using the magnetic annealing process.

scholarly journals Structural, morphological, optical, magnetic and ferroelectric properties of Ba0.2La0.8Fe2O4 nanofibers

2019 ◽  
Vol 9 (5) ◽  
pp. 4243-4247 ◽  
Keyword(s):  
Ferroelectric Properties ◽  
Xrd Analysis ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Loop Analysis ◽  
Loop Area ◽  
Transmission Electron ◽  
The Face ◽  
Face Centered ◽  
The Fourier Transform

The structural, morphological, optical, magnetic, and ferroelectric properties were studied for the Ba0.2La0.8Fe2O4 (BLF) through hydrothermal method. The face-centered cubic structure is confirmed from the X-Ray diffraction (XRD) analysis with some impurities. The particle size calculated from XRD is 21 nm. The Fourier transform infrared spectroscopy (FTIR) revealed the spinel structure of the synthesized samples. The surface morphology analyzed with the help of field emission scanning electron microscopy, transmission electron microscope. In addition, UV- Visible spectroscopy was used for the energy band gap (Eg) estimation and it is found as 2.05 eV. The M-H loop analysis makes clear that the synthesized samples have low magnetization with a small loop area. The P-E loop analysis expressed the ferroelectric nature of the synthesized sample.

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