1,936 research outputs found
Strong vortex-antivortex fluctuations in the type II superconducting film
The small size vortex-antivortex pairs proliferation in type II
superconducting film is considered for the wide interval of temperatures below
Tc. The corresponding contribution to free energy is calculated. It is shown
that these fluctuations give the main contribution to the heat capacity of the
film both at low temperatures and in the vicinity of transition
Spin crossover: the quantum phase transition induced by high pressure
The relationship is established between the Berry phase and spin crossover in
condensed matter physics induced by high pressure. It is shown that the
geometric phase has topological origin and can be considered as the order
parameter for such transition.Comment: 4 pages, 3 figure
A new class of nodal stationary states in 2D Heisenberg ferromagnet
A new class of nodal topological excitations in a two-dimensional Heisenberg
model is studied. The solutions correspond to a nodal singular point of the
gradient field of the azimuthal angle. An analytical solution found for the
isotropic case. An effect of in-plane exchange anisotropy is studied
numerically. It results in solutions which are analogues of the conventional
out-of-plane solitons in the two-dimensional magnets.Comment: 5 figure
Multiphonon anharmonic decay of a quantum mode
A nonperturbative theory of multiphonon anharmonic transitions between energy
levels of a local mode is presented. It is shown that the rate of transitions
rearranges near the critical level number : at smaller the process
slows down, while at larger it accelerates in time, causing a jump-like
loss of energy followed by the generation of phonon bursts. Depending on
parameters, phonons are emitted in pairs, triplets etc.Comment: submitted to Europhys.Let
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