MAGNETIC BEHAVIOR OF MAGNESIUM DIBORIDE SUPERCONDUCTING THIN FILMS

2003 ◽  
Vol 17 (04n06) ◽  
pp. 597-601
Author(s):  
G. GRIMALDI ◽  
U. GAMBARDELLA ◽  
S. PACE ◽  
V. FERRANDOM ◽  
C. FERDEGHINI ◽  
...  
Keyword(s):  
Thin Films ◽  
Hysteresis Loops ◽  
Annealing Treatment ◽  
Magnetic Behavior ◽  
Anomalous Behavior ◽  
Zero Field ◽  
Superconducting Thin Films ◽  
Double Peak ◽  
Transverse Geometry ◽  
Field Approaches

We report the experimental results of the field H and temperature T dependent magnetization M measurements of MgB 2 superconducting thin films deposited by pulsed laser deposition. MgB 2 thin films were obtained from a precursor layer deposited in UHV at room temperaure from stoichiometric target, then an annealing treatment in Mg atmosphere allowed to crystallize the superconducting phase. From the hysteresis loops at each temperature of measurement the critical current density Jc(H) has been extracted according to Brandt's model for a transverse geometry. At low temperatures an anomalous behavior has been observed in the hysteresis loops: as the exernal magnetic field approaches the zero field region on the upper and lower branches, a double peak of the magnetization occurs. This magnetic flux jumping can be explained within an adiabatic critical state model, and can be ascribed to thermomagnetic instabilities as in bulk samples.

scholarly journals Iron-Doped Lithium Tantalate Thin Films Deposited by Magnetron Sputtering: A Study of the Iron Role in the Structure and the Derived Magnetic Properties

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 50 ◽  
Author(s):  
Sergio David Villalobos Mendoza ◽  
José Trinidad Holguín Momaca ◽  
José Trinidad Elizalde Galindo ◽  
Diana María Carrillo Flores ◽  
Sion Federico Olive Méndez ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Blocking Temperature ◽  
Ferromagnetic Behavior ◽  
Zero Field ◽  
Cooling Curves ◽  
X Ray Diffraction ◽  
Field Cooling

Fe-doped LiTaO3 thin films with a low and high Fe concentration (labeled as LTO:Fe-LC and LTO:Fe-HC, respectively) were deposited by magnetron sputtering from two home-made targets. The dopant directly influenced the crystalline structure of the LiTaO3 thin films, causing the contraction of the unit cell, which was related to the incorporation of Fe3+ ions into the LiTaO3 structure, which occupied Li positions. This substitution was corroborated by Raman spectroscopy, where the bands associated with Li-O bonds broadened in the spectra of the samples. Magnetic hysteresis loops, zero-field cooling curves, and field cooling curves were obtained in a vibrating sample magnetometer. The LTO:Fe-HC sample demonstrates superparamagnetic behavior with a blocking temperature of 100 K, mainly associated with the appearance of Fe clusters in the thin film. On the other hand, a room temperature ferromagnetic behavior was found in the LTO:Fe-LC layer where saturation magnetization (3.80 kAm−1) and magnetic coercivities were not temperature-dependent. Moreover, the crystallinity and morphology of the samples were evaluated by X-ray diffraction and scanning electron microscopy, respectively.

Magnetic Anisotropy of Strained La0.7Sr0.3MnO3 Thin Films Studied by MOKE

2001 ◽  
Vol 690 ◽  
Author(s):  
M. Koubaa ◽  
A.M. Haghiri-Gosnet ◽  
P. Lecoeur ◽  
W. Prellier ◽  
B. Mercey
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Scaling Law ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Growth Conditions ◽  
Structural Quality ◽  
Lattice Strains ◽  
Stress States

ABSTRACTThe effects of the growth conditions and the lattice strains of pulsed laser deposited (PLD) La0.7Sr0.3MnO3 (LSMO) thin films upon the magnetic behavior have been studied using magneto-optical Kerr effect (MOKE) at room temperature. First, the structural quality of the films was investigated by XRD and the surface morphology was studied using AFM. It is shown that both surface morphology and crystallinity are optimized when the target-to-substrate distance and the oxygen pressure are chosen in agreement with a PD3 scaling law. Secondly, hysteresis loops have been recorded along the [100], [110] and [001] directions and the easy directions of magnetization have been determined for both stress states, i.e. tension on SrTiO3 and compression on LaAlO3. In tensile films, the whole plane is found to be easy, whereas, in compressive films, the easy axis should be an intermediate direction between the film's plane and its normal. Moreover, tensile films deposited under optimized growth conditions exhibit the largest anisotropy coefficient (K1eff = -6.9×105 erg/cm3).

Ferroelectricity, ferromagnetism, and magnetoelectric coupling in highly textured thin films of the multiferroic Pb(Fe0.5Nb0.5)O3

2012 ◽  
Vol 1454 ◽  
pp. 51-56 ◽  
Author(s):  
Oscar Raymond-Herrera ◽  
Paola Góngora-Lugo ◽  
Carlos Ostos ◽  
Mario Curiel-Alvarez ◽  
Dario Bueno-Baques ◽  
...  
Keyword(s):  
Thin Films ◽  
Hysteresis Loops ◽  
Rf Magnetron Sputtering ◽  
Magnetoelectric Coupling ◽  
Ferroelectric Materials ◽  
Zero Field ◽  
Different Temperatures ◽  
Ferroelectric Hysteresis ◽  
First Time ◽  
Magnetization Behavior

ABSTRACTA study of the ferroelectric and magnetic properties and of the magnetoelectric coupling effects of Pb(Fe0.5Nb0.5)O3 (PFN) thin films, grown on SrRuO3/Si [(100) or (111)] substrates by the rf-magnetron sputtering technique, is presented. Structural, morphological, and compositional characterization was realized using the XRD, AFM, XPS, and TEM techniques. Highly textured single phase films with different thickness (from 45 to 270 nm) were successfully grown without Fe2+ presence. A vertically [110] oriented grainy structure was observed. Polarization vs. electric field (P-E) hysteresis loops exhibit excellent and almost constant values of the maximum (∼ 60 μC/cm2) and remanent (∼ 22 μC/cm2) polarizations in the temperature range from 4 K to room temperature; small values of the coercive field, characteristic of soft ferroelectric materials, are observed in these samples. Measurements of the zero-field cooled (ZFC) and field cooled (FC) magnetization behavior and magnetic (M-H) hysteresis loops were realized at different temperatures between 5 and 300 K. Proof of the existence of ferromagnetic order in the low temperature region (below to 50 K) is discussed and reported for the first time. Values of the maximum (∼ 3 emu/g) and remanent (∼ 1.5 emu/g) magnetizations were obtained. dc magnetic field dependence of the ferroelectric hysteresis loops are shown as evidence of the magnetoelectric coupling.

Magnetic behavior of both superconducting thin films and their deposition targets

1988 ◽  
Vol 63 (8) ◽  
pp. 4199-4201 ◽  
Author(s):  
K. Moorjani ◽  
J. Bohandy ◽  
F. J. Adrian ◽  
B. F. Kim ◽  
U. Atzmony ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Behavior ◽  
Superconducting Thin Films

Microstructure study of Y–Ba–Cu oxide superconducting thin films

1988 ◽  
Vol 3 (6) ◽  
pp. 1311-1316 ◽  
Author(s):  
A. H. Hamdi ◽  
J. V. Mantese ◽  
A. L. Micheli ◽  
R. A. Waldo ◽  
Y. L. Chen ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Rutherford Backscattering Spectrometry ◽  
Analytical Techniques ◽  
Anomalous Behavior ◽  
Superconducting Thin Films ◽  
X Ray Diffraction ◽  
Sheet Resistivity ◽  
X Ray ◽  
Ion Channeling

Grain growth as a function of annealing temperature in Y–Ba–Cu oxide superconducting thin films is presented. Effects of excess Cu on the temperature dependence of the resistance, grain growth, and sheet resistivity are discussed. This is the first systematic study of the microstructure of thin films formed by the nonvacuum technique of metallo organic deposition. The Cu-rich films show an anomalous behavior in the resistivity at 220–240 K. The presence of excess Cu was found to enhance grain growth for films annealed below the melting point of the 1–2–3 phase. Films deposited on 〈100〉 SrTiO3 and rapid thermal annealed showed partial epitaxial growth of the 1–2–3 phase. The analytical techniques of Rutherford backscattering spectrometry, ion channeling, x-ray diffraction, scanning electron microscopy, electron microprobe analysis, sheet resistivity, and temperature versus resistance measurements have been used in this study.

Laser ablated pure non-crystalline Co thin films for inductors for ultra-high frequencies

2001 ◽  
Vol 674 ◽  
Author(s):  
V. Madurga ◽  
J. Vergara ◽  
C. Favieres
Keyword(s):  
Thin Films ◽  
Domain Walls ◽  
Spontaneous Magnetization ◽  
Magnetic Domain ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Soft Magnetic ◽  
High Frequencies ◽  
Magnetic Domain Walls ◽  
Deposited Films

ABSTRACTNon-crystalline Co thin films have been prepared by pulsed laser ablation deposition. From the M-H hysteresis loops measurements, a soft magnetic behavior is observed. Néel type magnetic domain walls are observed in the as-deposited films. The spontaneous magnetization, Ms(T = 300 K), is ≍ 860 emu/cm3. After annealing at 500 oC, Ms(T = 300 K) is ≍ 1460 emu/cm3. The extrapolated to zero K resistance decreases almost two orders of magnitude from the as deposited samples to the crystallized heated at 500 °C ones. A trilayer Co/Cu/Co has shown a real part magnetic susceptibility of 120 at 100 MHz. In the 100 MHz to 1 GHz frequency range, a perpendicular bias magnetic field increased this value up to 270, remaining almost constant for all range.

scholarly journals Critical Current and Pinning Features of a CaKFe4As4 Polycrystalline Sample

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6611
Author(s):  
Armando Galluzzi ◽  
Antonio Leo ◽  
Andrea Masi ◽  
Francesca Varsano ◽  
Angela Nigro ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Polycrystalline Sample ◽  
Critical Parameters ◽  
Zero Field ◽  
Critical Current Density Jc ◽  
Field Cooling

We analyze the magnetic behavior of a CaKFe4As4 polycrystalline sample fabricated by a mechanochemically assisted synthesis route. By means of DC magnetization (M) measurements as a function of the temperature (T) and DC magnetic field (H) we study its critical parameters and pinning features. The critical temperature Tc has been evaluated by M(T) curves performed in Zero Field Cooling-Field Cooling conditions. These curves show the presence of a little magnetic background for temperatures above Tc, as also confirmed by the hysteresis loops M(H). Starting from the M(H) curves, the critical current density Jc of the sample has been calculated as a function of the field at different temperatures in the framework of the Bean critical state model. The Jc(H) values are in line with the ones reported in the literature for this typology of samples. By analyzing the temperature dependence of the critical current density Jc(T) at different magnetic fields, it has been found that the sample is characterized by a strong type pinning regime. This sample peculiarity can open perspectives for future improvement in the fabrication of this material.

Vector Magneto-Optical Generalized Ellipsometry on Passivated Permalloy Slanted Columnar Thin Films

2012 ◽  
Vol 1408 ◽  
Author(s):  
Daniel Schmidt ◽  
Chad Briley ◽  
Eva Schubert ◽  
Mathias Schubert
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Three Dimensional ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Atomic Layer ◽  
Optical Coupling ◽  
Nanostructured Thin Film ◽  
Coupling Parameters ◽  
Columnar Thin Film

ABSTRACTVector magneto-optical generalized ellipsometry on passivated ferromagnetic permalloy slanted columnar thin films is reported. The nanostructured thin film was grown by electron-beam glancing angle deposition and subsequently coated with a thin Al2O3 layer by atomic layer deposition. Magneto-optical generalized ellipsometry data have been acquired while an external magnetic field H with constant amplitude was rotated with respect to the sample (spatial hysteresis loops). The magneto-optical coupling parameters, which are proportional to the sample magnetization M, reveal intriguing anisotropic magnetic behavior of the slanted columnar thin film. Three-dimensional graphs of the magneto-optical coupling parameters with respect to spatial hysteresis loops shown here are representative for the sample magnetization.

Structure and Magnetic Properties of Co2.73Fe0.27O4 Synthesized by the Heat-Decomposition Method

2011 ◽  
Vol 181-182 ◽  
pp. 352-355
Author(s):  
Zhang Hua Gan ◽  
Jun Bo Guo ◽  
Jing Liu ◽  
Zhi Hong Lu
Keyword(s):  
Decomposition Method ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Annealing Treatment ◽  
Exchange Interactions ◽  
Xrd Analysis ◽  
Zero Field ◽  
Bias Effect ◽  
Exchange Bias Effect ◽  
Field Cooling

Co2.73Fe0.27O4 nanoparticles were synthesized using the heat-decomposition method followed by annealing treatment. X-ray diffraction (XRD) analysis shows that most of the peaks are close to the data for antiferromagnetic Co3O4, while weak peaks of CoFe2O4 are also detected. It indicates that the prepared particles can be reckoned as a composite with a small size of the FM particles embed in a large thickness of the AFM matrix. The magnetic hysteresis loops of Co2.73Fe0.27O4 powders were measured at 10 K by using the zero-field cooling (ZFC) and field cooling (FC) procedures and show negative and downward shifts, and the shifts finally disappear when temperature increases to 200 K. We suggest that exchange bias effect in Co2.73Fe0.27O4 is mainly related with the exchange interactions at the interfaces between the FM CoFe2O4 nanoparticles and the frozen spins around them.

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