1,716 research outputs found
Doping-induced quantum cross-over in ErTiSnO
We present the results of the investigation of magnetic properties of the
ErTiSnO series. For small doping values the ordering
temperature decreases linearly with while the moment configuration remains
the same as in the parent compound. Around doping level we
observe a change in the behavior, where the ordering temperature starts to
increase and new magnetic Bragg peaks appear. For the first time we present
evidence of a long-range order (LRO) in ErSnO () below
mK. It is revealed that the moment configuration corresponds to a
Palmer-Chalker type with a value of the magnetic moment significantly
renormalized compared to . We discuss our results in the framework of a
possible quantum phase transition occurring close to .Comment: accepted in PRB Rapi
On the Pairwise Nonorthogonality Problem in Quantum Chemistry
It is shown that, starting from a set of local hybrid orbitals
if>; (i = 1, . .. n) one can construct pairwise nonorthogonal set of
functions Xi (i = 1, ... n) with the following feature calculated by employing maximum overlap criterion or by max,imizim.
g the average distance between the centroids of charge of the
electronic pairs. The use of the pairwise nonorthogonal functions
is advantageous in semiempirical methods since it minimizes the
error introduced by the neglect of the many-center electron
repulsion integrals
On the Topological Spectra of Composite Molecular Systems
It has been shown that topological spectrum of some large
molecules comprises the complete set of eigenvalues of the topological
matrix of some of their constituting fragments. Several relationships
between the coefficients of the fragmental eigenvectors and
those of the composite system have been derived. Some sufficient
conditions that a system comprise a spectrum of its parts have been
found and their use illustrated
Calculation of the Non-Bonding Molecular Orbitals in the Hulckel Theory
A method is given to obtain all NBMO\u27s for both alternant
and nonalternant aromatic hydrocarbons. In addition few theorems
are derived which can be used to deduce some (or all) of the
NBMO\u27s directly from the graph of the molecule
Two-step transition in a magnetoelectric ferrimagnet Cu2OSeO3
We report a detailed single crystal investigation of a magnetoelectric
ferrimagnet Cu2OSeO3 using dc magnetization and ac susceptibility along the
three principal directions [100], [110] and [111]. We have observed that in
small magnetic fields two magnetic transitions occur, one at Tc = 57 K and the
second one at TN = 58 K. At Tc the non-linear susceptibility reveals the
emergence of the ferromagnetic component and below Tc the magnetization
measurements show the splitting between field-cooled and zero-field-cooled
regimes. Above 1000 Oe the magnetization saturates and the system is in a
single domain state. The temperature dependence of the saturation below Tc can
be well described by m(T) = m(0)[1 - (T/Tc)^2]^{\beta}, with m(0) = 0.56
(mu)B/Cu, corresponding to the 3-up-1-down configuration. The dielectric
constant measured on a thin single crystal shows a systematic deviation below
the transition, indicating an intrinsic magnetoelectric effect.Comment: accepted for publication in PR
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