1,669 research outputs found
Degenerate self-similar measures, spectral asymptotics and small deviations of Gaussian processes
We find the logarithmic small ball asymptotics for the -norm with
respect to a degenerate self-similar measures of a certain class of Gaussian
processes including Brownian motion, Ornstein - Uhlenbeck process and their
integrated counterparts.Comment: 15 pages, 1 figur
Pressure-induced spin-state transition of iron in magnesiow\"ustite (Fe,Mg)O
We present a detailed theoretical study of the electronic, magnetic, and
structural properties of magnesiow\"ustite FeMgO with in the
range between 00.875 using a fully charge self-consistent implementation of
the density functional theory plus dynamical mean-field theory (DFT+DMFT)
method. In particular, we compute the electronic structure and phase stability
of the rock-salt B1-structured (Fe,Mg)O at high pressures relevant for the
Earth's lower mantle. We obtain that upon compression paramagnetic (Fe,Mg)O
exhibits a spin-state transition of Fe ions from a high-spin to low-spin
(HS-LS) state which is accompanied by a collapse of local magnetic moments. The
HS-LS transition results in a substantial drop of the lattice volume by about
48 %, implying a complex interplay between electronic and lattice degrees of
freedom. Our results reveal a strong sensitivity of the calculated transition
pressure upon addition of Mg. While for Fe-rich
magnesiow\"ustite, Mg , exhibits a rather weak variation
at 80 GPa, for Fe-poor (Fe,Mg)O it drops, e.g., by about 35 % to 52 GPa
for Mg . This behavior is accompanied by a substantial change of the
spin transition range from 50140 GPa in FeO to 3090 GPa for . In
addition, the calculated bulk modulus (in the HS state) is found to increase by
12 % from 142 GPa in FeO to 159 GPa in (Fe,Mg)O with Mg . We
find that the pressure-induced HS-LS transition has different consequences for
the electronic properties of the Fe-rich and poor (Fe,Mg)O. For the Fe-rich
(Fe,Mg)O, the transition is found to be accompanied by a Mott insulator to
(semi-) metal phase transition. In contrast to that, for , (Fe,Mg)O
remains insulating up to the highest studied pressures, implying a Mott
insulator to band insulator phase transition at the HS-LS transformation.Comment: 9 pages, 9 figure
Fully developed triplet proximity effect
We present a model for fully developed triplet proximity effect in
superconductor-ferromagnet heterostructures.
Within the circuit-theory approximation, we evaluate the Green's functions,
the density of states, and the Josephson current that depend essentially on the
magnetization configuration.Comment: 4 pages, 4 figure
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