اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدCrystal-fields in YbInNi4 determined with magnetic form factor and inelastic neutron scattering
64
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The magnetic form factor of YbInNi4 has been determined via the flipping ratios R with polarized neutron diffraction and the scattering function S(Q,w) was measured in an inelastic neutron scattering experiment. Both experiments were performed with the aim to determine the crystal-field scheme. The magnetic form factor clearly excludes the possibility of a Gamma7 doublet as the ground state. The inelastic neutron data exhibit two, almost equally strong peaks at 3.2 meV and 4.4 meV which points, in agreement with earlier neutron data, towards a Gamma8 quartet ground state. Further possibilities like a quasi-quartet ground state are discussed.
قيم البحث
اقرأ أيضاً
We present data on the magnetic and magneto-elastic coupling in the hexagonal multiferroic manganite LuMnO3 from inelastic neutron scattering, magnetization and thermal expansion measurements. We measured the magnon dispersion along the main symmetry
directions and used this data to determine the principal exchange parameters from a spin-wave model. An analysis of the magnetic anisotropy in terms of the crystal field acting on the Mn is presented. We compare the results for LuMnO3 with data on other hexagonal RMnO3 compounds.
We have investigated the phonon and the magnetic excitations in LaCoO3 by inelastic neutron scattering measurements. The acoustic phonon dispersions show some characteristic features of the folded Brillouin zone (BZ) for the rhombohedrally distorted
perovskite structure containing two chemical formula units of LaCoO3 in the unit cell. We observed two transverse optical (TO) phonon branches along (delta, delta, delta), consistent with previously reported Raman active Eg modes which show remarkable softening associated with the spin-state transition [Ishikawa et al., (Phys. Rev. Lett. 93 (2004) 136401.)]. We found that the softening takes place in the TO mode over the whole BZ. In contrast, the acoustic phonons show no anomalous softening associated with the spin-state transition. The low-energy paramagnetic scattering at 8 K is weak, increasing towards a maximum at E > 15 meV, consistent with excitation of the nonmagnetic low-spin to magnetic intermediate-spin state of Co 3+ ions.
We use neutron scattering to study the Pr$^{3+}$ crystalline electric field (CEF) excitations in the filled skutterudite PrOs$_4$As$_{12}$. By comparing the observed levels and their strengths under neutron excitation with the theoretical spectrum an
d neutron excitation intensities, we identify the Pr$^{3+}$ CEF levels, and show that the ground state is a magnetic $Gamma_4^{(2)}$ triplet, and the excited states $Gamma_1$, $Gamma_4^{(1)}$ and $Gamma_{23}$ are at 0.4, 13 and 23 meV, respectively. A comparison of the observed CEF levels in PrOs$_4$As$_{12}$ with the heavy fermion superconductor PrOs$_4$Sb$_{12}$ reveals the microscopic origin of the differences in the ground states of these two filled skutterudites.
Inelastic neutron scattering (INS) experiments under applied magnetic field at low temperatures show detailed low lying magnetic excitations in the so called tridiminshed iron icosahedron magnetic molecule. The magnetic molecule consists of nine iron
Fe$^{3+}$ ($s = 5/2$) and three phosphorous atoms that are situated on the twelve vertices of a nearly perfect icosahedron. The three phosphorous atoms form a plane that separates the iron cluster into two weakly coupled three- and six-ion fragments, {Fe$_3$} and {Fe$_6$}, respectively. The magnetic field INS results exhibit an $S=1/2$ ground state expected from a perfect equilateral triangle of the {Fe$_3$} triad with a powder averaged $g$-value $=2.00$. Two sets of triplet excitations whose temperature and magnetic field dependence indicate an $S=0$ ground state with two non-degenerate $S=1$ states are attributed to the {Fe$_6$} fragment. The splitting may result from a finite coupling between the two fragments, single-ion anisotropy, antisymmetric exchange couplings, or from magnetic frustration of its triangular building blocks.
Below about 150 K, the spin arrangement in the chain arrays of Sr14Cu24O41 is shown to develop in two dimensions (2D). Both the correlations and the dispersion of the observed elementary excitations agree well with a model of interacting dimers. Alon
g the chains, the intra- and inter-dimer distances are equal to 2 and about 3 times the distance (c) between neighboring Cu ions. While the intra-dimer coupling is J about 10 meV, the inter-dimer couplings along and between the chains are of comparable strenght, J// about -1.1 meV and Jperp about 1.7 meV, respectively. This remarkable 2D arrangement satisfies the formal Cu valence of the undoped compound. Our data suggest also that it is associated with a relative sliding of one chain with respect to the next one, which, as T decreases, develops in the chain direction. A qualitative analysis shows that nearest inter-dimer spin correlations are ferromagnetic, which, in such a 2D structure, could well result from frustration effects.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
