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1.
The interactions of slow magnetic monopoles with ferromagnetic materials are studied. The spin-flip cross section σ and the energy loss dE/dx are calculated for magnetic monopoles impinging parallel to the magnetization direction. In iron, these reach a maximum at v/c ~ 3 × 10?4, where they take the value of 100 Å2 and 100 MeV/cm respectively. The electromagnetic signal of a monopole passing through a ferromagnet and the generation of spin waves are discussed. 相似文献
2.
V. G. Masheva J. N. Kotzev A. V. Apostolov 《Applied Physics A: Materials Science & Processing》1980,23(1):93-97
A theory allowing the full determination of the texture function of a polycrystalline ferromagnet with cubic symmetry of the
polycrystallites is developed. Standard group theoretical methods are used, which allow to make maximum use of the full symmetry
of the system, without imposing any restriction on the generality of the problem. The magnetocrystalline anisotropy energy
of the textured sample is expanded in spherical harmonics and the corresponding energy of the crystallites is expanded in
a series of symmetry-adapted spherical harmonics. The texture function is expanded in a series of symmetry-adapted generalized
spherical harmonics. A relation between the coefficients of these expansions is determined. It is shown that the texture function
can be experimentally calculated using torque curves. 相似文献
3.
K.H.J. Buschow P.G. van Engen R. Jongebreur 《Journal of magnetism and magnetic materials》1983,38(1):1-22
The authors have studied the magneto-optical Kerr rotation in more than 200 metallic systems comprising alloys as well as intermetallic compounds of 3d transition metals. For all these materials the crystal structure, the lattice constants, the room temperature magnetization and the room temperature Kerr rotation at two different wavelengths are specified. For several series of ternary compounds, comprising Heusler alloys Ni2 In-type compounds and Cr23C6 type compounds, we determined the saturation moment at 4.2 K. For a number of representative alloys or compounds a study was also made of the wavelength dependence of the complex polar Kerr effect. The values of the Kerr rotation obtained at 633 nm were compared with the corresponding values of the measured magnetization. Systematic trends were observed and have been used to classify metallic systems into systems where the Kerr rotation will not reach values much in excess of 1° and systems where higher values are likely to be found. 相似文献
4.
《Physics letters. A》1987,123(1):37-38
Experiments done on fracture of ferromagnetic materials with non-magnetic grips and an effective magnetic shield have indicated that there is no emission of magnetic fields. It is concluded that previous reports of sizeable magnetic field emission are due to lack of proper precautions in the experimental set-up. 相似文献
5.
Using the Landau theory of phase transitions, Arrott plots, the high field and the paramagnetic susceptibility and the magnetization of heterogeneous weakly ferromagnetic alloys are calculated analytically for a simple model for the heterogeneity. 相似文献
6.
Granular materials have been conventionally used for acoustic treatment due to their sound absorptive and sound insulating properties. An emerging field is the study of the acoustical properties of multiscale porous materials. An example of these is a granular material in which the particles are porous. In this paper, analytical and hybrid analytical-numerical models describing the acoustical properties of these materials are introduced. Image processing techniques have been employed to estimate characteristic dimensions of the materials. The model predictions are compared with measurements on expanded perlite and activated carbon showing satisfactory agreement. It is concluded that a double porosity granular material exhibits greater low-frequency sound absorption at reduced weight compared to a solid-grain granular material with similar mesoscopic characteristics. 相似文献
7.
8.
The voltage which is generated during the reversal of the magnetization inside the ferromagnetic specimen itself is measured. This internally produced voltage is sensitive to external forces and internal stresses. The method is compared with the application of strain gages. 相似文献
9.
A. F. Orlov L. A. Balagurov I. V. Kulemanov N. S. Perov E. A. Gan’shina A. S. Semisalova A. D. Rubacheva V. I. Zinenko Yu. A. Agafonov V. V. Saraikin 《Physics of the Solid State》2012,54(2):283-286
Magnetic and magnetooptical properties of the Cr-doped GaN layers have been investigated in the temperature range 50–400 K.
A high saturation magnetization of 25 G has been observed in the obtained material. Spectra of the magnetooptical transversal
Kerr effect have revealed strong magnetic response in the energy range less than 3.0 eV due to the appearance of new spin-polarization
states in the band gap of GaN upon Cr doping. 相似文献
10.
11.
The ferromagnetic resonance is considered for a thin granular film consisting of spherical metal particles. It is shown that the interparticle dipole interactions lead to a noticeable shift of the resonance field and a strong asymmetry of absorption line. The free induction signal is time modulated and its envelopem ind(t) obeys the law ln (m ind) ≈t 2/3. The role of the particle shape in considered system is also discussed. 相似文献
12.
13.
P. Lázpita J. M. Barandiarán J. Gutiérrez M. Richard S. M. Allen R. C. O'Handley 《The European physical journal. Special topics》2008,158(1):149-154
Structural and magnetic transition temperatures of
ferromagnetic shape memory alloys present a strong dependence on
slight departures from the stoichiometry, as does the mobility of
twin boundaries responsible for the large magnetic field induced
strains. In this work we study four non stoichiometric Ni-Mn-Ga
polycrystalline alloys with compositions of 43–52 at.% nickel,
excess manganese and deficient in gallium, and a single crystal of
composition Ni52Mn26Ga22. Those compounds are of
technical interest due to the observed large room temperature
magnetic field induced strains. Calorimetric and magnetic
measurements determined the martensitic transition and Curie
temperatures of the alloys (AS = 331 K and
TCurie = 366 K for 52 at.% nickel alloy).
Nickel defective alloys present a martensitic transition region
broader than excess nickel ones. Neutron powder diffraction analysis
confirmed orthorhombic martensitic structures for nickel defective
alloys, and tetragonal for excess nickel ones. In the 52 atomic %
nickel alloys case the crystallographic structure of the martensitic
phase was also obtained on a single crystal with the same
composition, trained to get a single variant in agreement with
determined in the powder sample. 相似文献
14.
The magnetic properties of a charged spin-1 Bose gas with ferromagnetic interactions are investigated within mean-field theory. It is shown that a competition between paramagnetism, diamagnetism and ferromagnetism exists in this system. It is shown that diamagnetism, being concerned with spontaneous magnetization, cannot exceed ferromagnetism in a very weak magnetic field. The critical value of reduced ferromagnetic coupling of the paramagnetic phase to ferromagnetic phase transition [Formula: see text] increases with increasing temperature. The Landé-factor g is introduced to describe the strength of the paramagnetic effect which comes from the spin degree of freedom. The magnetization density [Formula: see text] increases monotonically with g for fixed reduced ferromagnetic coupling [Formula: see text] as [Formula: see text]. In a weak magnetic field, ferromagnetism makes an immense contribution to the magnetization density. On the other hand, at a high magnetic field, the diamagnetism tends to saturate. Evidence for condensation can be seen in the magnetization density at a weak magnetic field. 相似文献
15.
The properties of the stochastic magnetic structure of ultradispersed ferromagnetic materials are studied. The correlation
coefficients of the magnetization of a magnetic material are calculated for various types of chaos in the anisotropy field.
The effects of different types of disorder on the parameters of a stochastic magnetic structure are compared. Numerical simulations
by various methods confirm the theoretical results.
Fiz. Tverd. Tela (St. Petersburg) 41, 1432–1436 (August 1999) 相似文献
16.
Arcady Zhukov Carlos Garcia Maxim Ilyn Rastislav Varga Juan Jose del Val Alexander Granovsky Valeria Rodionova Mihail Ipatov Valentina Zhukova 《Journal of magnetism and magnetic materials》2012
We studied magnetic and structural properties of granular CoxCu100−x (5<x<40 at%), Cu63Fe37 and Heusler-type Ni2MnGa glass-coated microwires. We found that the structure of Co–Cu microwires consists of two phases: fcc Cu for all the samples and fcc α-Co present for higher Co content. In the case of low Co content, Co atoms are distributed within the Cu matrix. The quantity and the size of grains strongly depend on the geometry of the microwire. Co–Cu and Fe–Cu microwires exhibited considerable magnetoresistance (MR). For CoxCu100−x microwires at x≥30 the anisotropic contribution to MR has been observed. Temperature dependences of magnetization measured without an external magnetic field (ZFC) and in the presence of a field (FC) show considerable difference below 20 K, indicating the presence of small α-Fe or Co grains embedded in the Cu matrix. Annealed Ni2MnGa microwires showed ferromagnetic behavior with Curie temperature about 330 K and polycrystalline structure with space group I4/mmm and lattice parameters a=3.75 Å and c=6.78 Å. 相似文献
17.
J. Bartolomé L.M. García F. Bartolomé F. Luis F. Petroff C. Deranlot F. Wilhelm A. Rogalev 《Journal of magnetism and magnetic materials》2007
Magnetization and susceptibility measurements have been performed on Co granular (Al2O3/Co/Pt)25 multilayers. A cusp-like anomaly is present in the susceptibility, which together with magnetization measurements suggests that the samples behave as an amorphous Correlated-Super-Spin system. The presence of CoPt partial alloying is proven by the XANES spectra. The XMCD spectra show that the interfacial Pt atoms become magnetically polarized by hybridization of the Pt 5d and Co 3d electrons, and are ferromagnetically coupled to the Co particle moments. The Pt layer is effective in transmitting interparticle exchange coupling. 相似文献
18.
This report presents a comprehensive review of the magnetic properties of lithium ferrite materials. The fundamental properties are considered first. These include crystal structure, magnetization, magnetocrystalline anisotropy, and magnetostriction. The extrinsic magnetic properties, which are related to microwave applications, are then examined. These include coercive force, remanence, and microwave loss. Finally, a systematic review of the effects of substituents, including titanium, zinc, manganese, cobalt, and bismuth, is presented. 相似文献
19.
J.M. Wesselinowa 《Solid State Communications》2006,137(5):278-281
The effect of external magnetic field, temperature and film thickness on the spin wave energy and the spin-wave damping in thin ferromagnetic semiconducting films is studied using the s-d interaction model and a Green's function formalism beyond the random phase approximation. 相似文献
20.
Giant magnetoresistance (GMR) of sequentially evaporated Fe-Ag structures has been investigated. Direct experimental evidence is given, showing that inserting ferromagnetic layers into a granular structure significantly enhances the magnetoresistance. The increase in the GMR effect is attributed to spin polarization effects. The large enhancement (up to more than a fourfold value) and the linear variation of the GMR in low magnetic fields are explained by scattering of the spin polarized conduction electrons on paramagnetic grains. 相似文献