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1.
The coupling between localized magnetic moments via conduction electrons is calculated taking into account the temperature and the mean free path of the electrons. For a fully degenerate electron gas and an infinite electronic mean free path the oscillatory RKKY interaction is obtained. On the limit of Boltzmann population and for infinite electronic mean free path the interaction can only be ferromagnetic. Taking into account the electronic mean free path the possibility of antiferromagnetism is restored. Furthermore the range of the interaction decreases. Several intermediate cases and possible applications are discussed.  相似文献   

2.
The indirect interaction between localized magnetic moments in insulators and semiconductors is investigated at T = 0°K. This interaction arises from virtual excitations of the valence electrons to the conduction band and is oscillatory as a function of distance. The passage from the case of small gap semiconductors to insulators is studied in detail, as a function of the energy gap and the effective masses. The Bloembergen-Rowland interaction is derived as a limiting case for insulators. Possible applications are also discussed.  相似文献   

3.
《Physica A》1988,148(3):597-609
The methods of the indirect interaction operator derivation for the quantum particles locally coupled with the quasi-particles of another physical subsystem are reviewed. A variant of the consecutive canonical transformations method which allows one to obtain a nonperturbative solution of the problem is proposed for the systems which do not contain Fermi particles.  相似文献   

4.
《Physics letters. A》1986,115(4):169-172
We derive for the first time a first-principles theory of the magnetic suceptibility (χ) of Bloch electrons including the effects of periodic potential, spin-orbit interaction and localized magnetic moments, and believe it to be the most general and thorough treatment which has yet been made of this problem. The importance of the theory in possible applications is discussed.  相似文献   

5.
By using the band part of the Hubbard Hamiltonian as our starting point, we find that for one electron/atom, with Coulomb repulsion U and bandwidth Δ, there is a single band with sharp Fermi surface and enhanced Pauli paramagnetism for U < Δ, and a splitting into two symmetric bands with local moment formation for U > Δ.  相似文献   

6.
One-gluon exchange (OGE) corrections to the magnetic moments of the octet baryons are studied in the bag model. It is clarified that OGE resolves a problem of μ(Λ) and μ(Ξ?) in previous quark model calculations and also improves an overall agreement between theory and experiment.  相似文献   

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In order to probe quantitatively the effect of Kondo impurities on energy exchange between electrons in metals, we have compared measurements on two silver wires with dilute magnetic impurities (manganese) introduced in one of them. The measurement of the temperature dependence of the electron phase coherence time on the wires provides an independent determination of the impurity concentration. Quantitative agreement on the energy exchange rate is found with a theory by G?ppert et al. that accounts for Kondo scattering of electrons on spin-1/2 impurities.  相似文献   

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应用量子干涉理论和第一性原理研究了Co/Cu/Co夹层结构在[100]和[110]取向上振荡交换耦合及对磁层厚度的依赖,对夹层交换耦合振荡的计算结果表明:当相应的周期不变时,磁性层(Co)厚度的变化将导致在不同的RKKY振荡特征中势的再分配,磁层厚度发生变化时,磁性层上电子结构也发生变化,当磁性层较厚时,交换耦合仅在某一渐近值附近有一小的振荡。耦合振荡的周期、振幅和相位的测量与实验相一致,也与Barnas和Bruno 理论吻合。  相似文献   

11.
The origin of localized magnetic moments formation in metals is investigated theoretically using a self-consistent local spin density molecular cluster approach. Clusters with up to 55 atoms are employed to describe isolated impurity local moment behavior in the cases of FeAg and FePd. Densities of states and spin magnetic moments were determined and compared with results of spectroscopic (notably photoemission) and magnetization measurements, respectively. In the case of a noble metal host, the spin magnetization density is found to be highly localized around the Fe site; the iron moment is ≈ 3.9μB and the polarization of the host Ag atoms is small. In the case of a transition metal host, the iron moment is ≈ 3.2 μB but here the strong hybridization of the Fe-3d and Pd-4d states results in a large induced magnetic moment in the host PD metal — in essential agreement with experiment for this giant moment system.  相似文献   

12.
应用量子干涉理论和第一性原理研究了Co/Cu/Co夹层结构在[100]和[110]取向上振荡交换耦合及对磁层厚度的依赖,对夹层交换耦合振荡的计算结果表明:当相应的周期不变时,磁性层(Co)厚度的变化将导致在不同的RKKY振荡特征中势的再分配,磁层厚度发生变化时,磁性层上电子结构也发生变化,当磁性层较厚时,交换耦合仅在某一渐近值附近有一小的振荡.耦合振荡的周期、振幅和相位的测量与实验相一致,也与Barnas和Bruno理论吻合.  相似文献   

13.
In the cyclotron resonance (CR) spectra of two-dimensional (2D) electrons in InAs quantum wells, the CR line splitting is observed. The splitting is found to be an oscillating function of magnetic field. The oscillations do not correlate with the filling factor. The experimental results are interpreted in terms of the spin-orbit splitting in the presence of a built-in electric field appearing due to the asymmetry of the quantum-well potential. From the splitting of the CR line, the spin-orbit coupling constant αso is determined. The resulting value agrees well with the value obtained for the same sample from the Shubnikov-de Haas oscillations. The role of the resonance interaction of charge carriers in the well with the interface donor states is discussed.  相似文献   

14.
We present a theoretical and experimental study of electron-active cyclotron resonance in p-doped InMnAs in high magnetic fields. Results are based on an 8-band Pidgeon–Brown model generalized to include finite kz effects and s(p)–d exchange interaction between itinerant carriers and Mn d-electrons. The e-active transitions in the valence band in p-doped samples take place due to the nature of multiple valence bands (heavy and light holes). We have calculated the absorption spectra in high magnetic fields and identified optical transitions which contribute to the cyclotron resonance for both e-active and h-active polarizations. Calculations show agreement with experimental results.  相似文献   

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From the viewpoint of the spin-wave approach to the theory of ferromagnetic resonance, the first four moments of the absorption line are calculated in this paper. It is shown that in addition to the magnetic dipole-dipole interaction, the inhomogeneous exchange interaction which has been neglected in previous papers exerts substantial influence on the asymmetry and peakedness of the ferromagnetic resonance line.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 75–78, July, 1979.  相似文献   

18.
The magnetic properties of dilute Cu-Al alloys with 5 at.% Fe were measured in the solid and liquid states. The results are compared to the Scalapino formula for the susceptibility of dilute alloys. The transition from the magnetic to the non-magnetic state was observed at 41.5 at.% Al.  相似文献   

19.
A microscopic theory of spin fluctuations in an ensemble of electrons localized on donors in a bulk semiconductor has been developed. Both the hyperfine interaction of the electron spin with spins of host lattice nuclei and the exchange interaction between the electrons have been taken into account. A model of clusters to calculate spin noise spectra of the ensemble of localized charge carriers has been proposed. It has been shown that the electron-electron exchange interaction leads to an effective averaging of random nuclear fields and a shift of the peak in the spin-fluctuation spectrum towards lower frequencies.  相似文献   

20.
The special features of the antiferromagnetic resonance in metals in presence of a superconducting ordering are analyzed on the basis of the surface impedance. The indirect exchange interaction determines the shift of the resonace frequency and the spectrum of a new undamped mode near ωr. A parallel is drawn bettween the antiferromagnetic resonances in normal and superconducting states.  相似文献   

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