共查询到20条相似文献,搜索用时 15 毫秒
1.
Minamisono K Mantica PF Mertzimekis TJ Davies AD Hass M Pereira J Pinter JS Rogers WF Stoker JB Tomlin BE Weerasiri RR 《Physical review letters》2006,96(10):102501
The nuclear magnetic moment of the ground state of (57)Cu(Iota(pi) = 3/2(-), T(1/2) = 196.3 ms) has been measured to be /mu((57)Cu)/ = (2.00 +/- 0.05)mu(N) using the beta-NMR technique. Together with the known magnetic moment of the mirror partner (57)Ni, the spin expectation value was extracted as = -0.078 +/- 0.13. This is the heaviest isospin mirror T = 1/2 pair above the (40)Ca region for which both ground state magnetic moments have been determined. The discrepancy between the present results and shell-model calculations in the full f p shell giving mu((57)Cu) approximately 2.4mu(N) and approximately 0.5 implies significant shell breaking at (56)Ni with the neutron number N = 28. 相似文献
2.
V.P. Dyakonov M.T. Borowiec A. Jedrzejczak M. Górska N.A. Doroshenko E. Zubov Yu. Bukhantsev T. Zayarnyuk H. Szymczak 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):9-14
Magnetic phase transition in the CsDyW2O8 magnet has been studied by means of low temperature specific heat C
(
T
) measurements. The magnetic ordering temperature of the Dy3+ sublattice was established to be 1.34 K. The experimental results indicate on the antiferromagnetic character of interactions
between Dy3+ ions. The behavior of the C
(
T
) dependencies above and below T
N
is discussed in frames of different theoretical models. The measurements data on temperature and field dependencies of magnetization
are used to calculate the exchange and dipole-dipole interactions energy and to determine the possible magnetic structure
of the ground state.
Received 7 January 2002 / Received in final form 15 May 2002 Published online 7 September 2002 相似文献
3.
N. El Khayati R. Cherkaoui El Moursli J. Rodríguez-Carvajal G. André N. Blanchard F. Bourée G. Collin T. Roisnel 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(4):429-442
We have studied in detail the crystal and magnetic structures of the oxyphosphates MFePO5 (M: divalent transition metal) using neutron powder diffraction as a function of temperature. All of them are isomorphic
to the mixed valence compound α-Fe2PO5 with space-group Pnma. No disorder exists between the two metallic sites. The M2+O6 octahedra share edges between them and faces with Fe3+O6 octahedra building zigzag chains running parallel to the b-axis that are connected by PO4 tetrahedra. The topology of this structure gives rise to a complex pattern of super-exchange interactions responsible of
the observed antiferromagnetic order. The magnetic structures are all collinear with the spin directed along the b-axis except for M = Co. The experimental magnetic moments of Cu+2 and Ni2+ correspond to the expected ionic value, on the contrary the magnetic moment of Fe3+ is reduced, probably due to covalence effects, and that of Co2+ is greater than the spin-only value indicating a non negligible orbital contribution. Using numerical calculations we have
established a magnetic phase diagram adapted for this type of crystal structure and determined the constraints to be satisfied
by the values of the exchange interactions in order to obtain the observed magnetic structure as the ground state.
Received 15 December 2000 and Received in final form 25 June 2001 相似文献
4.
M. Krawiec B.L. Györffy J.F. Annett 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(2):163-176
We study the ground state properties of a superconductor-ferromagnet-insulator trilayer on the basis of a Hubbard Model featuring
exchange splitting in the ferromagnet and electron-electron attraction in the superconductor. We solve the spin-polarized
Hartree-Fock-Gorkov equations together with the Maxwell's equation (Ampere's law) fully self-consistently with respect to
the order parameter and the current. For certain values of the exchange splitting we find that a spontaneous spin polarized
current is generated in the ground state and is intimately related to Andreev bound states at the Fermi level. Moreover, the
polarization of the current strongly depends on the band filling.
Received 23 September 2002 / Received in final form 13 December 2002 Published online 1st April 2003
RID="a"
ID="a"e-mail: m.a.krawiec@bristol.ac.uk 相似文献
5.
D. Rudolph D. Weisshaar F. Cristancho J. Eberth C. Fahlander O. Iordanov S. Skoda Ch. Teich O. Thelen H.G. Thomas 《The European Physical Journal A - Hadrons and Nuclei》1999,6(4):377-380
The neutron g
9/2 single-particle state in 57Ni has been unambiguously identified in a combined measurement of the linear polarization, angular distribution, and angular
correlation of γ rays following the fusion-evaporation reaction 28Si(32S,2pn)57Ni at a beam energy of 90 MeV. The linear polarization was measured with a Euroball cluster detector and a prototype of an encapsulated six-fold segmented hexaconical Ge-detector. The spin of the 3701 keV
level in 57Ni was confirmed to be I= 9/2 and its parity determined to be positive.
Received: 24 September 1999 / Revised version: 22 October 1999 相似文献
6.
R. Zitzler Th. Pruschke R. Bulla 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(4):473-481
We discuss the ground state magnetic phase diagram of the Hubbard model off half filling within the dynamical mean-field theory.
The effective single-impurity Anderson model is solved by Wilson's numerical renormalization group calculations, adapted to
symmetry broken phases. We find a phase separated, antiferromagnetic state up to a critical doping for small and intermediate
values of U, but could not stabilize a Néel state for large U and finite doping. At very large U, the phase diagram exhibits an island with a ferromagnetic ground state. Spectral properties in the ordered phases are discussed.
Received 9 January 2002 Published online 25 June 2002 相似文献
7.
W.Z. Wang K.L. Yao 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):437-441
A ferrimagnetic polymer with m-phenylene skeleton as coupling unit is studied with the Hubbard model in the self-consistent mean-field theory. The ferrimagnetic
ground state with a total spin S = 1 per unit cell is obtained and originates from the antiferromagnetic correlations between the nearest neighbors. If the
on-site electron-electron repulsions at the radical sites and at the phenylene ring sites are different, the gap in energy
band structure may disappear and the ferrimagnetic ground state becomes unstable. The charge density and spin density can
transfer between the radical sites and the phenylene ring sites due to the competition between the hopping integral and the
on-site repulsion at different sites.
Received 15 July 2002 Published online 31 December 2002 相似文献
8.
A.N. Andreyev K. Van de Vel A. Barzakh A. De Smet H. De Witte D.V. Fedorov V.N. Fedoseyev S. Franchoo M. Górska M. Huyse Z. Janas U. Köster W. Kurcewicz J. Kurpeta V.I. Mishin K. Partes A. Plochocki P. Van Duppen L. Weissman 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):63-75
Alpha-decay properties of the neutron-deficient isotope 185Pb were studied at the PSB-ISOLDE (CERN) on-line mass separator using the resonance ionisation laser ion source (RILIS). The
nuclei of interest were produced in a 1.4 GeV proton-induced spallation reaction of a uranium graphite target. In contrast
to previous studies, two α-decaying isomeric states were identified in 185Pb. The relative production of the isomers, monitored by their α-counting rates, could be significantly changed when a narrow-bandwidth
laser at the RILIS setup was used to scan through the atomic hyperfine structure. Based on the atomic hyperfine structure
measurements, along with the systematics for heavier odd-mass lead isotopes, the spin and the parity of these states were
interpreted as 3/2- and 13/2+ and their nuclear magnetic moments were deduced. The α-decay energy and half-life value for the I
π = 13/2+ isomer are E
α = 6408(5) keV, T
1/2 = 4.3(2) s, respectively; while for the I
π = 3/2- isomer ( T
1/2 = 6.3(4) s) two α-decays with E
α1 = 6288(5) keV, I
α1 = 56(2)% and E
α2 = 6486(5) keV, I
α2 = 44(2)% were observed. By observing prompt α-γ coincidences new information on the low-lying states in the daughter isotope
181Hg was obtained.
Received: 7 February 2002 / Accepted: 19 February 2002 相似文献
9.
I. Procházka J. Koníček J. Dupák M. Finger M. I. Fominykh T. I. Kracíková V. N. Pavlov M. Petřík V. M. Tsupko-Sitnikov J. Muhonen 《Czechoslovak Journal of Physics》1981,31(5):522-526
Temperature dependence of the angular distribution anisotropy of the 212·0 keV gamma-ray following the decay of153Tb oriented in a gadolinium host was measured at temperatures from 16 to 70 mK. Magnetic dipole hyperfine splitting parameter a0 for153Tb(Gd) and magnetic dipole moment of the153Tb ground state were estimated to be ¦a
0¦1·2×10–5 eV and ¦¦3·1 nuclear magnetons, respectively.Authors are indebted to Dr. N. A. Lebedev, Yu. V. Yushkewich and the staff of the JINR synchrocyclotron for the preparation of the153Tb activity. The participation of Ing. L. Mare, J. Ferencei and S. I. Antonov in the measurements is also acknowledged. 相似文献
10.
A new method for extracting the hyperfine anomaly from experimental hyperfine structure constants is suggested. Instead of
independent high-precision measurements of the nuclear magnetic dipole moment, precise measurements of magnetic dipole hyperfine
interaction constants for two atomic states and a theoretical analysis can be used. This can lead to determination of hyperfine
anomaly for radioactive isotopes where the nuclear magnetic dipole moment is not known with high accuracy.
Received: 17 February 1998 相似文献
11.
D. Schwarzhans D. Zimmermann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(2):193-198
The absorption spectrum of NaAr has been investigated with high resolution using a supersonic beam of molecules and a tunable
dye laser. About 3 300 absorption lines due to the transition A
2
Π ←
X and B
2
Σ ←
X have been observed. In addition, we observed the spectral distribution of the fluorescence for a particular absorption line.
From all experimental data the X
2
Σ
+
interaction potential has been deduced in a fully quantum-mechanical method of approach. The potential is given in terms
of an analytical Hartree-Fock-Dispersion function. For the equilibrium parameters of the X state we get R
e
= 5.01(1) ? and D
e
= 41.6(2)
cm
-1
.
Received 28 August 2002 / Received in final form 15 October 2002 Published online 17 December 2002
RID="a"
ID="a"Now at Knick Elektronische Messger?te, Beuckestr. 22, 14163 Berlin, Germany.
RID="b"
ID="b"e-mail: dz@kalium.physik.tu-berlin.de 相似文献
12.
Ch. Lisdat N. Vanhaecke D. Comparat P. Pillet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):299-309
Two-photon photoassociation spectra in a Λ-type excitation scheme are analysed under the systematically varied experimental conditions of frequency detunings and laser
intensities. Line shape fits are presented as well as the investigation of intensity and detuning dependent line shifts. From
both we determine the attained spectroscopic precision, that is corrected for a systematic line shift due to the thermal distribution
of atoms in the trap. An energy correction for this effect is given. Information about the feasibility of generating translationally
cold molecules in a well defined rotational and vibrational level by the photoassociation process is derived from the analysis.
Received 21 May 2002 Published online 15 October 2002
RID="a"
ID="a"Current address e-mail: christian.lisdat@ptb.de
RID="b"
ID="b"e-mail: pierre.pillet@lac.u-psud.fr 相似文献
13.
P. Domokos T. Kiss J. Janszky 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):49-53
A beam of diatomic molecules scattered off a standing wave laser mode splits according to the rovibrational quantum state
of the molecules. Our numerical calculation shows that single state resolution can be achieved by properly tuned, monochromatic
light. The proposed scheme allows for selecting non-vibrating and non-rotating molecules from a thermal beam, implementing
a laser Maxwell's demon to prepare a rovibrationally cold molecular ensemble.
Received 23 August 2000 and Received in final form 17 November 2000 相似文献
14.
A.I. Vdovin A.N. Storozhenko 《The European Physical Journal A - Hadrons and Nuclei》1999,5(3):263-273
The renormalized random phase approximation for hot finite Fermi systems is evaluated with the use of the thermo field dynamics
formalism. This approximation treats vibrations of a hot finite Fermi system as harmonic ones but takes into account the Pauli
principle in a more proper way than the usual thermal RPA, thus incorporating a new type of correlations in a thermal ground
state. To demonstrate advantages of the approximation and to analyze a range of its validity, it is applied to the exactly
solvable Lipkin model. A comparison is made with the exact grand canonical ensemble calculations, results of the thermal Hartree
– Fock approximation and the thermal random phase approximation. The intrinsic energy of the system, the heat capacity, the
average value of the quasispin operator z-projection and the particle number variance are calculated as functions of temperature.
On the whole, the thermal renormalized RPA appears to be a better approximation than the other two. Its advantage is especially
evident in the vicinity of the phase transition point. It is found that within TRRPA the phase transition occurs at lower
temperature than in THFA and TRPA.
Received: 4 January 1999 / Revised version: 10 March 1999 相似文献
15.
Nuclear orientation measurements on dilute TbGd are analysed to yield the magnetic dipole and electric quadrupole moments of161Tb g.s. and multipole mixing ratios of transitions in161Dy. 相似文献
16.
17.
The reaction54Fe(α, n)57Ni has been used to implant57Co isotopes in ferromagnetic iron. Theg-factor of the lowest 3/2? state is determined using the internal field in a constant angle reversed field method. The angular correlation of the 127–1,378 keV cascade is also measured. The result of the angular correlation measurement together with reaction data is consistent withp 3/2 andp 1/2 single particle assignments to the lowest 3/2? resp. 1/2? state. In view of this statement the quenching of the magnetic moment is discussed. 相似文献
18.
A. Arima N. Yoshinaga Y.M. Zhao 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):105-107
We investigate the dominance of 0+ states as the lowest states in shell model calculations with random two-body interactions in a single j-shell. We have found an explanation of the large probability of the 0+ ground state.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
19.
C. Andreoiu D. Rudolph I. Ragnarsson C. Fahlander R.A.E. Austin M.P. Carpenter R.M. Clark J. Ekman R.V.F. Janssens T.L. Khoo F.G. Kondev T. Lauritsen T. Rodinger D.G. Sarantites D. Seweryniak T. Steinhardt C.E. Svensson O. Thelen J.C. Waddington 《The European Physical Journal A - Hadrons and Nuclei》2002,14(3):317-348
High-spin states in 59Cu were populated using the fusion-evaporation reaction 28Si + 40Ca at a beam energy of 122 MeV. The Gammasphere Ge-detector array in conjunction with the 4π charged-particle detector array
Microball allowed for the detection of γ-rays in coincidence with evaporated light particles. The resulting extensive high-spin
decay scheme of 59Cu is presented, which comprises more than 320 γ-ray transitions connecting about 150 excited states. Their spins and parities
have been assigned via directional correlations of γ-rays emitted from oriented states. Average quadrupole moments of rotational
bands have been determined from the analysis of residual Doppler shifts. Shell model calculations in the fp shell are invoked to study some of the low-spin states, while the experimental characteristics of the rotational bands are
analyzed in the configuration-dependent cranked Nilsson-Strutinsky (CNS) approach.
Received: 15 February 2002 / Accepted: 23 April 2002 相似文献
20.
C. J. Ashworth T. L. Shaw J. Rikovska N. J. Stone V. R. Green P. M. Walker B. D. D. Singleton I. S. Grant 《Hyperfine Interactions》1988,43(1-4):489-492
The sign of the nuclear magnetic dipole moment of the ground state of122I has been determined to be positive using a novel experimental technique. The technique investigates the asymmetry of positron
emission by detecting the 511 keV gamma-rays produced on the annihilation of the positrons. The method would appear to have
general validity for studying the sign of the magnetic moment in other cases where theβ
+ decay is relatively simple. 相似文献