共查询到20条相似文献,搜索用时 343 毫秒
1.
D.J. Kim 《Solid State Communications》1980,34(12):963-965
The effective exchange interaction due to phonons, Jph, is found to be ferromagnetic and enhanced with the Stoner exchange enhancement factor D0 to give . In addition, Jph is found to be further enhanced by phonon softening. These findings imply the fundamental importance of the phonon effects in itinerant electron magnetism. 相似文献
2.
Etude des proprietes thermodynamiques d'un groupement tetranucleaire: Application au compose Na3RuO4
The exact eigenvalues spectrum of the spin hamiltonian have been calculated for a tetranuclear cluster formed by four spins 3/2 at the vertices of a lozenge. Two isotrope exchange interactions J1 and J2 are able to explain the thermodynamic properties (magnetic susceptibility, entropy, specific heat). A ground state transition from singlet to triplet state occurs when the ratio reaches the value . The magnetic susceptibility data of Na3RuO4 fit well with the theoretical values proposed for and J2/k (?22,5 K). 相似文献
3.
The spin-wave spectrum of Ca2MnO4 has been measured at 4.2K. It can be fully built from two exchange integrals in the (001) plane meV and , and in out-of plane exchange integral . This latter explains quite well the splitting of the magnon dispersion curve. 相似文献
4.
The (1-0), (2-0), and (3-0) transitions of 15N16O and 15N18O are investigated. The wavenumbers of the rotation-vibration lines are reported for the overtone bands and the (1-0) subband. It is shown that in the data reduction it is advantageous to calculate first merged spectroscopic constants ignoring the Λ-type doubling. The vibrational constants ωe, ωexe, ωeye and the vibrational dependence of the rotational constants are determined. The study of 15N18O allows the determination of the equilibrium values of the centrifugal distortion correction ADe to the spin-orbit constant and of the spin-rotation constant γe from the isotopic invariance of the ratios and . It is found that and . 相似文献
5.
L.R. Testardi 《Solid State Communications》1975,17(7):871-874
The temperature dependence of the superconducting critical current density Jc(T) in zero applied field from 4.2 K to Tc has been measured for 15 films of Nb-Ge with varying composition, deposition conditions, and radiation damage. The results show (i) the enhanced superconductivity observed in stoichiometric Nb3Ge as well as nonstoichiometric films is “bulk like” rather than filamentary, (ii) a simple correlation of the form which is reasonably independent of how the Tc has been achieved, and (iii) some additional evidence that the enhanced Tc of the films is not due to their chemical composition alone. 相似文献
6.
Molecular beam electric resonance spectroscopy has been used to measure the l-type doubling transitions in carbonyl sulfide. Transitions in J = 4 to J = 20 have been observed for the (0220) vibrational state and for J = 1 and J = 2 for the (0310) state. The data has been analyzed to give the v = 2 energy separation , and the vibrational dependence of q to be 86.52(9)(v2 + 1) KHz. The dipole moment of the (0220) vibrational state is 0.6936(3) D. 相似文献
7.
Calculations of vibrational and rotational level spacings of homonuclear inert gas diatomic molecules by numerical integration of the radial Schrödinger equation are presented. The potentials which were used for the ground states of Ar2, Kr2, and Xe2 were obtained from accurate fits to the molecular beam scattering data. From the calculated and Bv's, the following spectroscopic constants (in cm?1) were fitted: for Ar2ωe = 31.92, ωexe = 3.31, ωeye = 0.11, Be = 0.060, αe = 0.004; for , , , , ; for , , , , . 相似文献
8.
The wavenumbers of the rotation-vibration lines of 14N16O are reported for the (2-0) and (3-0) bands. The full set of spectroscopic constants for the three bands (1-0), (2-0), and (3-0) has been determined with the method developed by Albritton, Schmeltekopf, and Zare for merging the results of separate least-squares fits. The vibrational constants ωe, ωexe, ωeye, and the vibrational dependence of the rotational constants have been deduced. The apparent spin-orbit constant and its centrifugal correction (including the spin-rotation constant) have a vibrational dependence of the following form: and ; the values of the constants in these two equations have been determined. 相似文献
9.
The magnetic susceptibility measurements of orthorhombic U(OH)2SO4 within the temperature range 4.2–300 K have revealed a magnetic anomaly at TD = 21 K associated with crystallographic transition induced by the cooperative Jahn-Teller effect. Above 21 K the magnetic susceptibility of the uranium (4+) ion corresponds to the electronic ground doublet confirming thus the antiprismatic symmetry (D4d) of the crystal field at the uranium site. Below TD the system of two singlets ()|2〉 ± ()|〉 separated by δ(T) is the ground state of the uranium ion. 相似文献
10.
To investigate dynamical (time-dependent) behavior of spins and spin clusters in the two-dimensional ± J Ising spin-glass, we have evaluated the relaxation time τi of individual spins by the Monte Carlo simulation. An interesting finding is that, at least in the temperature range , most of τi are described by with T0?0.5J (Ei being a constant), which suggests that the system undergoes a glass transition obeying Fulcher's law. 相似文献
11.
A millimeter-wave spectrometer having a sensitivity of 4 × 10?10 cm?1 in the 2-mm region has been constructed for observation of extremely weak millimeter-wave spectra of gases. It has been used to measure J → J, K = 0 ← 3 transitions in PH3 and J → J, K = 0 ← 3 as well as K = ±1 ← ±4 transitions in PD3. The B0 and C0 spectral constants (in MHz) are: for PH3, B0 = 133 480.15 ± 0.12 and C0 = 117 488.85 ± 0.16; for PD3, B0 = 69 471.10 ± 0.03 and C0 = 58 974.37 ± 0.05. The effective ground-state values obtained for the bond angle and bond length are: for PH3, and ; for PD3, and . The corresponding zero-point-average values were calculated to be: for PH3, and ; for PD3, and . For both species, the equilibrium values are and . 相似文献
12.
Measurements of the microwave spectrum of the C4v molecule IF5 in the excited vibrational states v5(B1) = 1 and v9(E) = 1 are reported for the transitions J4 → 5, 5 → 6, 6 → 7, 8 → 9, and 9 → 10 (27–55 GHz). The Coriolis resonance interaction between these two states is analyzed by diagonalization of Hamiltonian matrices of dimension 3 × (2J + 1) in which all (Δl,Δk) = (±2, ±2)(q+), (±2, ±2)(q?), and (0, ±4)(R6) interactions are included as off-diagonal terms in addition to the v5 = 1 ? v9 = 1, l9 = ±1(R59) Coriolis interaction. In the v9 = 1 state spectra, the l-doubling of the kl = ?1 transitions and splittings of the kl = ?3 transitions and splittings of the kl = +3 transitions, all enhanced by the Coriolis resonance, have been observed and measured. Least-squares refined rovibrational parameters for the v5 = 1 and v9 = 1 states are reported and a preliminary value for the rotational constant C9 has been obtained. 相似文献
13.
B.P. Antonyuk 《Solid State Communications》1978,25(12):971-975
A possibility of the central peak appearance in crystals with low concentration of small-radius polarons is pointed out. The intensity of the central peak increases sharply with the softening of the phonon mode in the vicinity of the structural phase transition . The peak width γ0 is determined by the probability W of the polaron hopping between the sites γ0 = K02a2W. 相似文献
14.
Using the Bohm-Pines hamiltonian the problem of the bound state of two plasmons is investigated following two different decoupling procedures where the energy transfer or 2ωpl. The effective interaction g4 between the two plasmons is found to be repulsive for and attractive when . The case of is shown to be analogous to the situation under which the critical coupling g4c is determined. 相似文献
15.
R.L. Collins 《Physics letters. A》1977,61(1):71-74
Experimental evidence using Josephson junction devices has suggested that Johnson noise in copper fails to be proportional to absolute temperature below 10 millikelvin. A microscopic theory is presented which gives the Johnson noise temperature coth () dX where . For copper, the calculated T0 = 3.84 mK agrees closely with the value extracted from experimental data, 3.89 mK. Within a few percent, coth (), and this adequately fits the available experimental data. νF is the fermi velocity and N is the length of the resistor. The Johnson noise parameter “T0” presumably can measure νF along different crystal orientations. 相似文献
16.
H. Falk 《Physica A》1980,104(3):475-479
The (discrete-time) Glauber model is considered for a one-dimensional system of spins sj = ±1 with nearest-neighbor Ising interaction . The Jj = ±J are treated as random variables with an arbitrary joint probability p(J). The exact time-dependent average 〈sj〉t is determined, and from it the “quenched” average is explicitly found. 相似文献
17.
Parametric interaction of strong waves () with a cold, two-fluid (ion and electron) plasma is studied in the limits of high frequency (ωo?ωLe) and resonance (ωo ≈ ωLe). Unstable oscillations of both electrons and ions are found in the resonance limit. 相似文献
18.
For the model at T = 0 four susceptibilities have been calculated exactly on a sequence of finite square lattices and extrapolated to the infinite square lattice. For the ferromagnet χzz = 0 while χxx ~ N2.9; for the antiferromagnet and . 相似文献
19.
C. Uberoi 《Physics letters. A》1980,76(1):69-71
The frequencies of the two modes of surface plasmon oscillations exhibited by coated semiconductor spheres can either decrease or increase with the size of the particle depending upon the ratio , ?∞1 and ?∞2. When ωh1 = ωh2, the soft mode frequency becomes independent of the size of the sphere. 相似文献
20.
The infrared spectrum of yttrium monoiodide has been excited in an electrodeless microwave discharge and explored between 2500 and 12 000cm?1 with a high-resolution Fourier transform spectrometer. A unique system is observed (ν00 = 9905.520 cm?1), which we attribute to a transition and an extensive analysis is made. Rovibrational constants are obtained for both states mainly from a simultaneous multiband fitting. This procedure is applied to the whole set of 2231 observed line wavenumbers in the 1-0, 0-0, and 0–1 bands, yielding a final weighted standard deviation of 0.0038 cm?1. Furthermore, a partial analysis of the 2-0 and 3-1 bands is performed. The following equilibrium constants are derived (cm?1): High-order constants Dv and Hv are also calculated for the various vibrational levels (v′ = 0, 1, 2, 3; v″ = 0, 1). 相似文献