共查询到20条相似文献,搜索用时 156 毫秒
1.
J. G. M. Armitage R. G. Graham P. C. Riedi H. Figiel S. F. J. Cox C. A. Scott J. S. Abell K. Yoshimura 《Hyperfine Interactions》1991,64(1-4):395-399
All previous experiments have suggested that Y(Co1−x
Al
x
)2 is a weak itinerant ferromagnet for 0.12<x<0.20. The muon transverse damping rate (λ) increases rapidly near the Curie point forx≥0.155 and for one sample withx=0.145. The value of λ increases with decreasing temperature for other samples withx<0.155 but shows no feature at the Curie point. 相似文献
2.
E. A. Melezhik Zh. V. Gumenyuk-Sychevskaya 《Bulletin of the Lebedev Physics Institute》2010,37(1):6-7
Currently, CdTe/Cd
x
Hg1-x
Te/CdTe heterostructures attract particular interest and are very promising for developing the next-generation terahertz radiation
detectors. However, properties of such structures have not yet been studied in sufficient detail. The energy spectrum and
wave functions of the CdTe/Cd
x
Hg1-x
Te/CdTe heterostructure were theoretically modeled for various well widths, the valence band offset, and composition x in the range 0<x<0.16. Characteristic features of the behavior of energy levels of two-dimensional electrons in such structures were studied
with respect to x variation. A criterion for determining the number of electronic levels below the conduction band bottom, applicable to compositions
0<x<0.16 was obtained. The time of two-dimensional electron relaxation by longitudinal optical phonons was calculated. 相似文献
3.
A. G. Razumnaya A. G. Rudskaya M. F. Kupriyanov Yu. V. Kabirov 《Physics of the Solid State》2009,51(11):2304-2307
The room-temperature stability region of the tetragonal phase in the Y1 − x
Ca
x
MnO3 solid solution system has been found for the first time. The concentration boundaries between this phase and the orthorhombic
(x > 0.5) and hexagonal (x < 0.25) phases are sensitive to the sample preparation conditions. The coexistence of the hexagonal and tetragonal phases
in the range 0.15 < x < 0.25 indicates that these phases undergo a first-order reconstructive phase transition. Preliminary measurements of magnetic
ordering effects for compositions with x = 0.3, 0.5, and 0.7 have been performed. 相似文献
4.
T. I. Arbuzova I. B. Smolyak S. V. Naumov A. A. Samokhvalov A. V. Mostovshchikov N. I. Solin 《Journal of Experimental and Theoretical Physics》1999,89(5):899-905
Solid solutions of the system La1−x
CaxMnO3 are synthesized, and their magnetic and electrical properties are investigated. As x is increased, the crystal lattice changes symmetrically from an orthorhombic (x=0 and x=0.8) to a cubic structure (0<x⩽0.6 and x=1). Nonstoichiometric LaMnO3 and compositions with a low Ca content (0<x<0.4) are collinear ferromagnets. A metal-insulator transition is observed in them near the Curie temperature. Compositions
with 0.6⩽x⩽0.9 exhibit a semiconductor-type conductivity and an unusual temperature behavior of the magnetization and the susceptibility
with very distinct Curie and Néel temperatures. The magnetic properties of the solid solutions are explained on the basis
of the model of ferro-antiferromagnetic phase separation.
Zh. éksp. Teor. Fiz. 116, 1664–1675 (November 1999) 相似文献
5.
A. N. Chabanyuk V. I. Torgashev Yu. I. Yuzyuk V. V. Lemanov P. Simon 《Physics of the Solid State》2009,51(1):165-173
The temperature (295 K < T < 650 K) investigations of the polarized Raman spectra measured for a single-crystal sample of the Pb0.54Ca0.46TiO3 solid solution in the frequency range 10 < ν < 1200 cm−1 have established the existence of at least one specific temperature (T
c
≈ 392 K) at which the oscillator parameters of phonon modes exhibit noticeable anomalies. Similar phenomena are observed
in solutions with 0.4 < x < 0.5. A sharp increase in the intensity of the spectral lines corresponding to polarization waves at temperatures immediately
below T
c
suggests a transformation of Pb1 −x
Ca
x
TiO3 (0.4 < x < 0.5) into a polar state, which does not exist for x > 0.5.
Original Russian Text ? A.N. Chabanyuk, V.I. Torgashev, Yu.I. Yuzyuk, V.V. Lemanov, P. Simon, 2009, published in Fizika Tverdogo
Tela, 2009, Vol. 51, No. 1, pp. 155–163. 相似文献
6.
J. Zhu S. L. Ban S. H. Ha 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(2):67
The binding energy of an exciton screened by the electron-hole plasma in a wurtzite
GaN/In
x
Ga1−x
N quantum well (in
the case of 0.1 < x < 1 within which the interface phonon
modes play a dominant role) is calculated including the exciton-phonon interaction by a
variational method combined with a self-consistent procedure. The coupling between the
exciton and various longitudinal-like optical phonon modes is considered to demonstrate
the polaronic effect which strongly depends on the exciton wave function. All of the
built-in electric field, the exciton-phonon interaction and the electron-hole plasma
weaken the Coulomb coupling between an electron and a hole to reduce the binding energy
since the former separates the wave functions of the electron and hole in the
z direction and the later two enlarge the exciton Bohr radius. The
electron-hole plasma not only restrains the built-in electric field, but also reduces the
polaronic effect to the binding energy. 相似文献
7.
N. E. Sluchanko V. V. Glushkov S. V. Demishev M. V. Kondrin N. A. Samarin V. V. Brazhkin I. Braunserade V. V. Moshchalkov 《Physics of the Solid State》1999,41(1):1-7
Galvanomagnetic characteristics of the A1−x
Six solid solutions (x<12 at. %) have been studied within a broad range of temperatures (1.8–290 K) and magnetic fields (up to 15 T). An anomaly
in the concentration dependence of the Hall coefficient R
H
(x,T=290 K) has been revealed near the boundary of absolute instability (x<8.5 at. %) of compounds in the Al1−x
Six series. The variation of the Hall coefficient and of the magnetoresistance in the A1−x
Six series at low (T<77 K) temperatures is analyzed within models taking into account the anisotropy in conduction-band electron scattering.
Fiz. Tverd. Tela (St. Petersburg) 41, 3–10 (January 1999) 相似文献
8.
9.
O. Yu. Shevchenko R. R. Akhunzyanov V. Yu. Lavrentyev 《The European Physical Journal C - Particles and Fields》2011,71(8):1713
The first moments of the polarized valence parton distribution functions (PDFs) truncated to the wide Bjorken x region 0.004<x<0.7 are directly (without any fitting procedure) extracted in the next to leading order (NLO) QCD from both COMPASS and HERMES
data on pion production in polarized semi-inclusive DIS (SIDIS) experiments. The COMPASS and HERMES data are combined in two
ways and two scenarios for the fragmentation functions (FFs) are considered. Two procedures are proposed for an estimation
of light sea quark contributions to the proton spin. Both lead to the conclusion that these contributions are compatible with
zero within the errors. 相似文献
10.
Yu. M. Baikov S. E. Nikitin Yu. P. Stepanov V. M. Egorov 《Physics of the Solid State》1997,39(5):729-734
The electrical conductivity of ceramic samples with a general formula HxBa2YCu3O7+z
has been measured in the course of hydrogenation (formation of the hydrocuprate) and subsequent oxidation (formation of the
oxyhydrocuprate). The hydrocuprate (x>0, −0.1<z<0) was synthesized by exposing the parent Ba2YCu3O6.9 ceramic to hydrogen at a temperature of 450 K and a pressure of 50 kPa. The oxyhydrocuprate (x=2, z⩽1.5) was prepared by treating the preliminarily hydrogenated ceramic of composition H2Ba2YCu3O6.9 with oxygen at 470 K at a pressure of 70 kPa. The four-probe dc method was used in the electrophysical measurements. The
measurements were performed in the temperature interval 300–450 K and within the compositional ranges 0<x<2.1, −0.1<z<1.5. The resistivity of the samples increases by nearly six orders of magnitude with hydrogenation from x=0 to x=2, and decreases by three orders of magnitude with oxidation, changing from z=−0.1 to z=0.8 for x=2. The electrode polarization effect is observed, which is apparently caused by ionic processes occurring at the electrode-ceramic
interface. Water vapor is experimentally found to exert considerable effect on the electrophysical parameters of the hydrocuprate-copper
electrodes system.
Fiz. Tverd. Tela (St. Petersburg) 39, 823–828 (May 1997) 相似文献
11.
G. V. Loseva S. G. Ovchinnikov É. K. Yakubailik N. I. Kiselev T. A. Gaidalova 《Physics of the Solid State》1998,40(10):1715-1717
A study has been made of the FexV1−x
S solid solutions with 0<x<0.5. For the compounds with x>0.1, x-ray diffraction analysis discloses a V5S8 superstructure. Samples with x>0.1 are magnetically ordered at room temperature. The concentration dependences of resistivity and magnetization exhibit
sharp peaks for x=0.1 and x=0.2, respectively. The main features of the structure and electronic properties have been qualitatively explained in terms
of the three-band exciton-insulator model, and the maxima in resistivity and magnetization are assigned to the formation of
localized magnetic moments with S=1, which become delocalized with increasing x.
Fiz. Tverd. Tela (St. Petersburg) 40, 1890–1893 (October 1998) 相似文献
12.
An X-ray diffraction and 57Fe Mössbauer spectroscopy investigation of Si100– x Fe x (0?<?x?<?80) thin films prepared by combinatorial sputtering methods is reported. Resulting Mössbauer spectra were fit to Voigt-based distributions of quadrupole doublets for paramagnetic spectral components and Zeeman split sextets for ferromagnetic spectral components. In conjunction with the X-ray measurements, these results show that the Si-rich films are a mixture of dilute Fe in amorphous Si and an approximately equiatomic amorphous SiFe phase. Fe-rich films show the presence of a ferromagnetically ordered phase. For x?<?73, this ferromagnetic phase is amorphous or nanostructured and for x?≥?73, the phase is shown to be a crystalline bcc phase. Results are discussed in terms of short-range structural ordering in these alloys. 相似文献
13.
L. S. Smirnov I. Natkaniec A. B. Belushkin D. Smith M. Prager 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(6):847-856
Neutron scattering is used to study the structure and dynamics of Me1 − x
(NH4)
x
SCN (Me = K, Rb) mixed crystals along the concentration section of 0.0 < x < 1.0 at room temperature 10 and 290 K. Phase transitions in Me1 − x
(NH4)
x
SCN mixed crystals are analyzed by neutron powder diffraction. The measured spectra of inelastic incoherent neutron scattering
from mixed crystals in a concentration range of 0.0 < x < 1.0 at 10 are transformed into the generalized phonon density of states G(E) in the one-phonon incoherent approximation. Using G(E), we determine the changes in ammonium ion dynamics during phase transitions. Low energy resonance and local translational
(two bands) and librational (two bands) modes are observed in the disordered rhombic phase at 10 K. The low energy resonance
mode is not found in the ordered monoclinic phase at 10 K, though the local translational mode in the form of two bands and
the local librational mode in the form of four bands are present there. The low energy resonance mode appears due to hybridization
of the phonon spectrum of the host crystal with rotational tunneling modes of the split librational ground state of the impurity’s
molecular ammonium ion. 相似文献
14.
M. Wilkinson B. Mehlig K. Gustavsson E. Werner 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(1):18
It might be expected that trajectories of a dynamical system which has no negative
Lyapunov exponent (implying exponential growth of small separations) will not cluster
together. However, clustering can occur such that the density
ρ(Δx) of trajectories within distance
|Δx| of a reference trajectory has a power-law divergence, so that
ρ(Δx) ∼ |Δx| −β
when |Δx| is sufficiently small, for some
0 < β < 1. We demonstrate this effect using a random map in
one dimension. We find no evidence for this effect in the chaotic logistic map, and argue
that the effect is harder to observe in deterministic maps. 相似文献
15.
Binary and ternary sulphide glasses, in contrast to their selenium counterparts, are usually not fully polymerized. This circumstance provides a means to examine the role of nanoscale phase separation effects on global elastic phase diagrams of disordered networks. In bulk Ge x As x S1 ? ?2 x glasses, the non-reversing enthalpy (ΔH nr) near T g is found to display a global minimum (~0) in the 0.11<x<0.15 range, the reversibility window. Furthermore, the ΔH nr term is found to age for glass compositions below (x<0.11) and above (x>0.15) the window, but not in the window. In analogy to corresponding selenides, glass compositions in the window represent the intermediate phase, those at x<0.11 are floppy, and those at x>0.15 stressed-rigid. Raman scattering shows floppy and stressed-rigid networks to consist of S8, and As4S4 and As4S3 monomers, respectively, aspects of structure that contribute to a narrowing of the intermediate phase and to suppression of the ΔH nr term in S-rich glasses qualitatively in relation to corresponding Se-rich glasses that are fully polymerized. 相似文献
16.
Natalija van Well Sitaram Ramakrishnan Ketty Beauvois Navid Qureshi Eric Ressouche Markos Skoulatos Robert Georgii Oksana Zaharko Sander van Smaalen 《Annalen der Physik》2020,532(7):2000147
The triangular antiferromagnetic Cs2CuCl4-xBrx mixed system is studied by neutron single-crystal diffraction in magnetic field. It shows a rich magnetic phase diagram consisting of four regimes depending on the Br concentration and is characterized by different exchange coupling mechanisms. For the investigated compositions from regime I (0 < x ≤ 1.5), a critical magnetic field Bc is found for a Br concentration x = 0.8 at Bc = 8.10(1) T and for x = 1.1 at Bc = 7.73(1) T and from regime IV (3.2 < x < 4) for x = 3.3 at Bc = 0.99(3) T. For magnetic fields larger than the respective Bc, magnetic superlattice reflections of these compounds are not found. The incommensurate magnetic wave vector q = (0, 0.470, 0) appears below the ordering temperature TN = 0.51(1) K for Cs2CuCl3.2Br0.8, and q = (0, 0.418, 0) below TN = 1.00(6) K for Cs2CuCl0.3Br3.7. Neutron diffraction experiments at around 60 mK for x = 3.7 in a magnetic field show the critical magnetic field at Bc = 7.94(16) T and the formation of the second magnetic phase at around 8.5 T depending on the temperature. Inelastic neutron scattering experiments for the compound from regime III (2 < x ≤ 3.2) with x = 2.2 show dynamical correlations at a temperature around 50 mK giving evidence for a spin liquid phase. 相似文献
17.
The Ni2 + x
Mn1 − x
Ga magnetic shape memory alloys at concentrations x = 0.18–0.36 have been studied using small-angle polarized neutron scattering in magnetic fields 0 < H ≤ 5.7 kOe. In this concentration range, the alloy undergoes a coupled magnetic-structural phase transition. At x < 0.18, the martensitic phase transition occurs, as usual, in the ferromagnetic state, i.e., T
m
< T
C (T
m
and T
C are the temperatures of the martensitic and magnetic phase transitions, respectively). However, at x > 0.27, the relationship between the characteristic temperatures is changed, i.e., T
m
> T
C. The small-angle polarized neutron scattering data indicate that, in the concentration range under investigation, there occurs
a complex transformation of the magnetic and atomic structures. All phase transitions exhibit a temperature hysteresis of
scattering and polarization, which is characteristic of first-order phase transitions. A comparative analysis of the mesoscopic
structures of the Ni2 + x
Mn1 − x
Ga and Ni2 + x + y
Mn1 − x
Ga1 − y
alloys studied using the small-angle polarized neutron scattering technique has been carried out. 相似文献
18.
G. M. Abramova G. A. Petrakovskii V. V. Sokolov D. A. Velikanov A. M. Vorotynov A. F. Bovina A. A. Amirov A. M. Aliev L. N. Khanov G. S. Patrin 《Physics of the Solid State》2012,54(3):531-536
This paper reports on first results of the synthesis and study of the thermal, structural, electrical, resonance, and magnetic
properties of new sulfide materials Me
x
Mn1 − x
S (Me = Cu, 0 < x < 0.2) synthesized based on manganese monosulfide. The materials have a NaCl cubic structure at 300 K and undergo a concentration
metal-insulator transition with increasing degree of substitution and with varying temperature. The magnetic transition occurs
in the region of the heat capacity anomaly. The Néel temperature is slightly dependent on the copper concentration. The samples
with a high copper content exhibit metallic conduction at T < 260 K and semiconductor conduction at T > 260 K. 相似文献
19.
The configurations at thermodynamic equilibrium of CoxAg201-x nanoparticles are explored for 0 < x < 201 by means of Metropolis Monte Carlo simulations with a semi-empirical embedded atom potential at temperatures from 100 K to 1000 K. Remarkable configurations are predicted in this temperature range. As a consequence of a competition between strain and Co binding at low temperature, for x < 20, Co is distributed just below the cluster surface layer into groups of no more than 5 atoms, favouring well-defined positions, and the cluster central area is avoided. To increase the temperature favours the clustering of these small groups. Their dissolution is predicted at temperatures higher than the melting temperature of the cluster. For x > 50, Co regroups at the centre of the cluster and intersects {111}-facets when Ag atoms are not numerous enough to form an entire surface shell. At these stoechiometries, temperature is not sufficient to mix Ag and Co, even above the melting point. At still smaller Ag concentrations, the Ag atoms are distributed at lowest coordination sites, along the edges of the cluster, avoiding the cluster facets as well as inner sites. At intermediate stoechiometries (20 < x < 50), either oblate Co groups below the surface or a compact group at the centre of the cluster are possible.Received: 1 October 2003, Published online: 27 January 2004PACS:
61.46. + w Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals - 61.43.Bn Structural modeling: serial-addition models, computer simulation 相似文献
20.
A. C. Felici N. Galbato D. Debowska T. Papa M. Piacentini F. Lama 《Il Nuovo Cimento D》1994,16(2):163-168
Summary We have measured at room temperature the photoacoustic spectra of Cd1−x
Fe
x
Te(0<x<0.055) around the CdTe fundamental absorption threshold. We identified an absorption band at (1.38±0.01) eV, increasing with
the Fe concentration, that we assigned to the5
E→3
T
1 transition within the Fe2+ (3d
6) manifold. We observed also a broadening and a shift to higher energies of the CdTe absorption edge for increasingx.
Work partially supported by the Italian Consorzio INFM and CNR through the GNSM. 相似文献