scholarly journals Asymmetric Hysteresis Loops in Co Thin Films

2020 ◽  
Vol 5 (4) ◽  
pp. 71
Author(s):  
Andrea Ehrmann ◽  
Tomasz Blachowicz
Keyword(s):  
Exchange Bias ◽  
Kerr Effect ◽  
Room Temperature ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Blocking Temperature ◽  
Optical Kerr Effect ◽  
Thin Film System ◽  
Magnetic Hysteresis Loops ◽  
Magneto Optical Kerr Effect

Asymmetric magnetic hysteresis loops are usually found in exchange bias (EB) systems, typically after field cooling a system below the Néel temperature of an antiferromagnet exchange coupled to a ferromagnet. Alternatively, asymmetric hysteresis loops may occur due to undetected minor loops or in systems with a rotational anisotropy. Here, we report on an exchange bias thin film system MgO(100)/Co/CoO, examined at room temperature, which is far above the blocking temperature, by the magneto-optical Kerr effect (MOKE). While the longitudinal hysteresis loops partly show steps which are well-known from diverse purely ferromagnetic systems, the transverse hysteresis loops exhibit clear asymmetries, similar to exchange biased systems at low temperatures, and unusual transverse magnetization values at saturation. Since minor loops and a rotational anisotropy can be excluded in this case, this asymmetry can possibly be a residue of the exchange bias coupling at lower temperatures.

scholarly journals Exchange bias in ferromagnetic bilayers with orthogonal anisotropies: the case of GaMnAsP/GaMnAs combination

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Suho Choi ◽  
Seul-Ki Bac ◽  
Xinyu Liu ◽  
Sanghoon Lee ◽  
Sining Dong ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Easy Axis ◽  
Initial Conditions ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
The Other ◽  
Planar Hall Effect ◽  
Magnetic Layers ◽  
Out Of Plane ◽  
Magnetic Hysteresis Loops

Abstract We report the observation of exchange bias in a ferromagnetic Ga0.94Mn0.06As0.77P0.23/ Ga0.94Mn0.06As bilayer, in which the easy axis in one layer is oriented out-of-plane, and in the other in-plane. Magnetization reversal in this system is explored using planar Hall effect (PHE) measurements under various initial conditions and with various field-cooling orientations. Our results show that the two magnetic layers are ferromagnetically exchange-coupled, and that such coupling results in pronounced exchange-bias-like shifts of magnetic hysteresis loops during reversal of in-plane magnetization. The presence of exchange bias in this system can be understood on the basis of magnetic closure domains formed in the layer with the out-of-plane easy axis.

Large room-temperature magneto-optical Kerr effect in CuCr2Se4−xBrx (x = 0 and 0.3)

1991 ◽  
Vol 93 ◽  
pp. 207-210 ◽  
Author(s):  
H. Brändle ◽  
J. Schoenes ◽  
P. Wachter ◽  
F. Hulliger ◽  
W. Reim
Keyword(s):  
Kerr Effect ◽  
Room Temperature ◽  
Optical Kerr Effect ◽  
Magneto Optical Kerr Effect

scholarly journals Room-temperature ultrafast carrier and spin dynamics in GaAs probed by the photoinduced magneto-optical Kerr effect

2001 ◽  
Vol 63 (23) ◽  
Author(s):  
A. V. Kimel ◽  
F. Bentivegna ◽  
V. N. Gridnev ◽  
V. V. Pavlov ◽  
R. V. Pisarev ◽  
...  
Keyword(s):  
Kerr Effect ◽  
Room Temperature ◽  
Spin Dynamics ◽  
Optical Kerr Effect ◽  
Ultrafast Carrier ◽  
Magneto Optical Kerr Effect

scholarly journals Ferroelectric and Magnetic Properties of Hot-Pressed BiFeO3-PVDF Composite Films

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Annapu V. Reddy ◽  
K. C. Sekhar ◽  
Navneet Dabra ◽  
A. Nautiyal ◽  
Jasbir S. Hundal ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Coercive Field ◽  
Polyvinylidene Fluoride ◽  
Room Temperature ◽  
Magnetic Hysteresis ◽  
Composite Films ◽  
Hysteresis Loops ◽  
Liquid Phase Sintering ◽  
Magnetic Hysteresis Loops ◽  
Ferroelectric Hysteresis

The ferroelectric and magnetic properties of hot-pressed BiFeO3- (BFO) polyvinylidene fluoride (PVDF) composite films have been studied. The BiFeO3 (BFO) ceramics have been synthesized by a rapid liquid phase sintering technique. The X-ray diffraction (XRD) studies revealed that the impure phase observed in pure BFO ceramics was significantly reduced in the composite films. The presence of both ferroelectric and magnetic hysteresis loops confirms the multiferroic nature of the composite films at room temperature. A well-saturated ferroelectric hysteresis loop with a remanent polarization (Pr)∼4.8 μC-cm-2 and coercive field (Ec)∼1.55 kV/cm has been observed in composite thin films at room temperature. The magnetic hysteresis loops were traced at room temperature with SQUID. The remanent magnetization (Mr)∼3.0×10−3 emu/gm and coercive field (Hc)∼0.99 kOe was observed in the composite film. The magnetic polarization of the composite films has found to be enhanced as compared to pure BFO and correlated to reduction in BFO impure peak intensity.

The Influence of CeO2-Doping of Nanosized Cadmium Ferrite on Catalytic Conversion of Ethanol

2020 ◽  
Vol 13 (2) ◽  
pp. 156-169
Author(s):  
Abdelrahman A. Badawy ◽  
Ahmed M. Rashad ◽  
Shaimaa M. Ibrahim ◽  
Sahar M. El-Khouly
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Magnetic Hysteresis ◽  
Maximum Yield ◽  
Hysteresis Loops ◽  
Ethanol Conversion ◽  
Ferrite Formation ◽  
Opposite Trend ◽  
Magnetic Hysteresis Loops

Background: The role of CeO2-doping (0.75-3 mol%) and calcination temperature on solid-solid interaction between ferric and cadmium oxides yielding cadmium ferrites was examined. Methods and Results: The results exposed that ceria improves the ferrite formation by heating at 600-700ºC via the dissolution of some dopant cation in the lattice of CdO with the subsequent creation of anionic vacancies and/or formation of higher valency cadmium cation (Cd(2+δ)+). SBET of solids calcined at 500oC increased by CeO2-doping, while opposite trend for solids calcined at 600 and 700oC. The magnetic hysteresis loops of all samples showed room-temperature ferromagnetism with different hysteresis loop shapes. Conclusion: Magnetization increased by CeO2-doping that might be due to the enhancement of cadmium ferrite formation. Ethanol conversion increased by increasing CeO2-doping. Dehydrogenation product (acetaldehyde) was mainly the yield of ethanol conversion. The maximum yield of acetaldehyde (92.97%) carried out for solids doped with 3 mol% CeO2.

Structural and Magnetic Properties of the Rapid Cooled Alloys: Fe60Co10Y5+xZr5-xB20 (Where: x = 0 or 2)

2019 ◽  
Vol 70 (1) ◽  
pp. 224-227
Author(s):  
Marcin Nabialek ◽  
Bartlomiej Jez ◽  
Kinga Jez ◽  
Katarzyna Bloch
Keyword(s):  
Room Temperature ◽  
Nanocrystalline Material ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Single Step ◽  
Magnetic Polarization ◽  
X Ray ◽  
High Temperature Alloys ◽  
Magnetic Hysteresis Loops ◽  
Vibration Magnetometer

This article presents the results of tests on high-temperature alloys, produced on the basis of the FeCoB matrix. The nanocrystalline material was produced in a single-step process of rapid cooling of liquid alloy that was injected into a copper mould. Alloy samples were obtained in the form of 10mm x 5mm x 0.5mm tiles. Studies of the structure of the manufactured alloys were undertaken using Bruker X-ray analysis equipment (featuring a CuKa lamp). The magnetic polarization of saturation was measured, as a function of temperature, using a Faraday magnetic balance; the measurements ranged from room temperature up to 850K. Through numerical analysis of the curves, the Curie temperature of the investigated alloys was determined. Using a vibration magnetometer, static magnetic hysteresis loops were measured. The magnetization of saturation of the tested alloys was greater than 1 T, while the coercive field values were 400 and 16600 A/m. The stiffness parameter of the spin wave Dspf was determined.

Morphology and Curie Temperature Changes upon Annealing of Co/W(110)

1997 ◽  
Vol 475 ◽  
Author(s):  
A. Bauer ◽  
A. Mühlig ◽  
T. Günther ◽  
M. Farle ◽  
K. Baberschke ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Ultrathin Films ◽  
Kerr Effect ◽  
Room Temperature ◽  
The Other ◽  
Scanning Tunneling ◽  
Optical Kerr Effect ◽  
Tunneling Microscopy ◽  
Temperature Changes ◽  
Magneto Optical Kerr Effect

ABSTRACTAnnealing of CoAV(110) ultrathin films causes rather strong changes of film morphology and magnetic properties, which has been studied by scanning tunneling microscopy (STM) and alternating-current magneto-optical Kerr effect (ac-MOKE). Annealing above 500 K of room-temperature grown 2 monolayers (ML) thick Co/W(110) films leads to the formation of islands and a decrease of the Curie temperature 7C. At 4 ML, on the other hand, a network of interconnected islands is formed upon annealing, resulting in an enhanced TC. While the increase of TC at 4 ML is explained by an increase of the local film thickness, the anomalous TC behavior at 2 ML is assigned to the occurrence of superparamagnetism.

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