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1.
Th. Gerrits H. A. M. van den Berg J. Hohlfeld O. Gielkens L. Br Th. Rasing 《Journal of magnetism and magnetic materials》2002,240(1-3):283-286
We have measured the response of a 20×10 μm, 8 nm thin NiFe (80:20) permalloy film due to excitation by short in-plane magnetic field pulses. We will show that using a two-pulse-technique a complete control of the precessional motion of the magnetisation can be achieved on picosecond timescales. Furthermore, we will present numerical calculations which show that a complete suppression of magnetisation ringing after switching can only be realised by a cascade of short field pulses. 相似文献
2.
B.P.C. Rao† S. Ramaswamy† C. Gopalakrishnan N. Satya Vijayakumar K.R. Ganesh 《哲学杂志》2013,93(25):3463-3473
Two-dimensional carbon nanosheets have been fabricated using inductively coupled radio frequency plasma-enhanced chemical vapour deposition. The structural properties of the nanosheets have been characterised using atomic force microscopy, scanning electron microscopy and X-ray diffractometer. The magnetisation of the samples was studied using vibrating sample magnetometer. The magnetisation of the nanosheets was found to be diamagnetic for fast synthesis processes (30 and 60 min). On the other hand, the nanosheets exhibited a weak ferromagnetic response for the slow (120 min) synthesis process. Energy dispersive spectrometry and atomic absorption spectroscopy confirmed that the magnetisation exhibited by the carbon nanosheets was an intrinsic property and that it was not due to contamination from the substrate. Raman spectroscopy studies revealed that the ferromagnetic carbon nanosheets have a higher ratio (1.20) of graphite peak (I G) to disordered peak (I D) than normally expected (0.75–0.90). Available data indicated that the magnetisation was due to the presence of structural disorders. 相似文献
3.
Eva Lucaccini Matteo Briganti Dr. Mauro Perfetti Dr. Laure Vendier Dr. Jean‐Pierre Costes Dr. Federico Totti Prof. Dr. Roberta Sessoli Prof. Dr. Lorenzo Sorace 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5552-5562
The magnetic behaviour of a Dy(LH)3 complex (LH? is the anion of 2‐hydroxy‐N′‐[(E)‐(2‐hydroxy‐3‐methoxyphenyl)methylidene]benzhydrazide) was analysed in depth from both theoretical and experimental points of view. Cantilever torque magnetometry indicated that the complex has Ising‐type anisotropy, and provided two possible directions for the easy axis of anisotropy due to the presence of two magnetically non‐equivalent molecules in the crystal. Ab initio calculations confirmed the strong Ising‐type anisotropy and disentangled the two possible orientations. The computed results obtained by using ab initio calculations were then used to rationalise the composite dynamic behaviour observed for both pure DyIII phase and YIII diluted phase, which showed two different relaxation channels in zero and non‐zero static magnetic fields. In particular, we showed that the relaxation behaviour at the higher temperature range can be correctly reproduced by using a master matrix approach, which suggests that Orbach relaxation is occurring through a second excited doublet. 相似文献
4.
M.D. Kuz'min 《Journal of magnetism and magnetic materials》2011,323(8):1068-1082
Possible shapes of high-field magnetisation curves of two-sublattice ferrimagnets are analysed within a model with two anisotropy constants for the subdominant sublattice. The model is relevant to 3d-4f intermetallic compounds. For the purpose of classification the magnetisation curves are regarded as ordered sequences of horizontal, slanted and vertical sections, without reference to quantitative details. Every shape type corresponds to a domain in the plane of relative anisotropy parameters κ1 and κ2. The κ1κ2 diagram proves rather complicated; however, in the limiting cases of very weak or very strong anisotropy (in relation to intersublattice exchange) it takes the same universal form characteristic of simple ferromagnets. 相似文献
5.
S.J. Collocott 《Journal of magnetism and magnetic materials》2010,322(16):2281-2286
Bulk amorphous ferromagnet alloys of composition Nd60Fe30Al10, Nd60Fe20Co10Al10 and Pr58Fe24Al18 have been prepared by argon arc melting and quenching into a copper mould. General insight into the magnetic behaviour of the alloys was gained from measurement of the major hysteresis loop at room temperature, and from zero-field cooled and field-cooled magnetisation measurements in the range 10-400 K. Measurements of the coercivity were made from 10 to 400 K, and for all alloys, the coercivity is seen to increase steeply with decreasing temperature to a peak at a temperature in the range 25-50 K, before decreasing. For all alloys, the temperature dependence of the coercivity between 50 and 400 K is well explained by the strong pinning model of domain walls of Gaunt [Philos. Mag. B 48 (1983) 261]. Quantities deduced from the Gaunt model, along with other relevant magnetic parameters, are used to estimate values for the exchange and anisotropy constants. 相似文献
6.
The magnetic configuration of a ferromagnetic system with mono-disperse and poly-disperse distribution of magnetic particles with inter-particle interactions has been computed. The analysis is general in nature and applies to all systems containing magnetically interacting particles in a non-magnetic matrix, but has been applied to steel microstructures, consisting of a paramagnetic austenite phase and a ferromagnetic ferrite phase, as formed during the austenite-to-ferrite phase transformation in low-alloyed steels. The characteristics of the computational microstructures are linked to the correlation function and determinant of depolarisation matrix, which can be experimentally obtained in three-dimensional neutron depolarisation (3DND). By tuning the parameters in the model used to generate the microstructure, we studied the effect of the (magnetic) particle size distribution on the 3DND parameters. It is found that the magnetic particle size derived from 3DND data matches the microstructural grain size over a wide range of volume fractions and grain size distributions. A relationship between the correlation function and the relative width of the particle size distribution was proposed to accurately account for the width of the size distribution. This evaluation shows that 3DND experiments can provide unique in situ information on the austenite-to-ferrite phase transformation in steels. 相似文献
7.
The results of a detailed structural and magnetic study clearly indicate that regardless of the thermal history of the samples,
Fe has a strong preference for the Ni sites in Ni-poor (nonstoichiometric) Ni75Al25 alloys. Fe substitution has a profound effect on the nature of magnetism in Ni25Al25
Article presented at the International Symposium on Advances in Superconductivity and Magnetism: Materials, Mechanisms and
Devices, ASMM2D-2001, 25–28 September 2001, Mangalore, India. 相似文献
8.
An extension of Bean's model, incorporating the observed exponential decay, with increasing field, of critical current density in the high-Tc superconductors, is developed. It is used for explaining the various features of the isothermal magnetisation curves. Using this model, a calculation is presented for the time-decay of magnetisation after the sample is exposed to a magnetic field, and also after this applied field is switched off. The field dependence of the decay rate in these two conditions is calculated, and then compared with available results on the 90 K and the 40 K class of oxide superconductors. The results, in the limit of field-independent current density, also agree qualitatively with experimental results for the heavy fermion superconductor CeCu2Si2. 相似文献
9.
Alessandro Chiolerio Paola Martino Paolo Allia 《Journal of magnetism and magnetic materials》2009,321(19):3099-3103
Structure, morphology and magnetic properties of thermally evaporated Co/Cr multilayers and of the solid solution obtained by isothermal treatment of the layered samples have been studied to evaluate their potential application as high-coercivity materials for hard spin injectors in spintronic devices such as magnetic tunneling junctions. The thermal treatment was performed in a partial pressure of inert gas to allow interdiffusion of Cr and Co. Structure and composition of the materials, as well as the effects of the annealing treatment, have been investigated by field emission scanning electron microscopy and energy-dispersive X-ray analysis. The magnetic configuration of these films was investigated by magnetic force microscopy. Simultaneous measurements of two mutually perpendicular magnetisation components were performed by means of a vector vibrating sample magnetometer, and showed that the in-plane coercivity can be increased by proper thermal treatment from less than 10 Oe to about 240 Oe. However, annealing may result in a loss of compositional and morphologic homogeneity of the films. 相似文献
10.
Tomasz Błachowicz 《Central European Journal of Physics》2005,3(2):147-162
This paper explains the Random Field Ising Model simulations of a two-dimensional ferromagnetic/antiferromagnetic interface,
influenced by the exchange-bias interaction. Exchange-biased shifts, coercivity fields, the number of unreversed spins as
well as the numerical errors are provided. These were tested for different structure dimensions and boundary conditions in
order to find limitations of the method. The algorithm developed is simple, very effective, and provides deeper insight into
the nature of the exchange-bias phenomenon. 相似文献