Search results for "Solid-state physics"
showing 10 items of 112 documents
Polarons in thet-J model
1991
A convenient form of the Peierls-Hubbard Hamiltonian is obtained for the case when the Hubbard repulsion is the largest energy parameter. It allows to consider in the spin-wave approximation the properties of the one-hole low-lying excitations of a 2d lattice. For the parameters approximately corresponding to La2CuO4 it is shown that the hole polarons in the CuO2 planes of lightly doped samples are of large size with a solitonlike-shaped highly asymmetric wave function oriented along the diagonals of the planes or of small size depending on the value of the electron-phonon coupling. In both cases the cooperative effect of the electron-phonon and electron-magnon interactions leads to a large…
Chiral excitations of magnetic droplet solitons driven by their own inertia
2019
The inertial effects of magnetic solitons play a crucial role in their dynamics and stability. Yet governing their inertial effects is a challenge for their use in real devices. Here, we show how to control the inertial effects of magnetic droplet solitons. Magnetic droplets are strongly nonlinear and localized autosolitons than can form in current-driven nanocontacts. Droplets can be considered as dynamical particles with an effective mass. We show that the dynamical droplet bears a second excitation under its own inertia. These excitations comprise a chiral profile, and appear when the droplet resists the force induced by the Oersted field of the current injected into the nanocontact. We …
Temperature-Dependent Change of the Electronic Structure in the Kondo Lattice System $YbRh_{2}Si_{2}$
2021
Seminar, Deutschland; Journal of physics / Condensed matter 00(00), 1-20 (2021). doi:10.1088/1361-648X/abe479
The Statistical Description of de Haas—van Alphen Oscillations in Silicon Nanosandwich
2020
Here, we present room temperature de Haas—van Alphen oscillations measured in silicon nanosandwich in a weak magnetic field. Our results demonstrate a decrease of the oscillation magnitude with increasing magnetic field strength. This behavior is drastically different from the results reported earlier and it is attributed to the low-dimensionality of the studied structure, which enables room temperature observation of the de Haas—van Alphen effect in moderate magnetic fields up to 1000 Oe. We employ the classic Lifshitz-Kosevich formalism based on the dependence of the carrier effective mass on the applied magnetic field, to statistically describe this effect. We note that the statistical a…
KPZ equation with realistic short-range-correlated noise
2003
We study a realistic simulation model for the propagation of slow-combustion fronts in paper. In the simulations the deterministic part of the dynamics is that of the KPZ equation. The stochastic part, including in particular the short-range noise correlations, is taken from images of the structure of real paper samples. The parameters of the simulations are determined by using an inverse method applied to the experimental front data and by comparing the simulated and the experimental effective-noise distributions. Our model predicts well the shape of the spatial and temporal correlation functions, including the location of the crossovers from short-range (SR) to long-range (LR) behavior. T…
Two-body contributions to the effective mass in nuclear effective interactions
2018
Starting from general expressions of well-chosen symmetric nuclear matter quantities derived for both zero- and finite-range effective theories, we derive the contributions to the effective mass. We first show that, independently of the range, the two-body contribution is enough to describe correctly the saturation mechanism but gives an effective mass value around $m^*/m \simeq 0.4$. Then, we show that the full interaction (by instance, an effective two-body density-dependent term on top of the pure two-body term) is needed to reach the accepted value $m^*/m \simeq 0.7-0.8$.
Predicting Neutrinoless Double Beta Decay
2005
We give predictions for the neutrinoless double beta decay rate in a simple variant of the A_4 family symmetry model. We show that there is a lower bound for the neutrinoless double beta decay amplitude even in the case of normal hierarchical neutrino masses, corresponding to an effective mass parameter |m_{ee}| >= 0.17 \sqrt{\Delta m^2_{ATM}}. This result holds both for the CP conserving and CP violating cases. In the latter case we show explicitly that the lower bound on |m_{ee}| is sensitive to the value of the Majorana phase. We conclude therefore that in our scheme, neutrinoless double beta decay may be accessible to the next generation of high sensitivity experiments.
Double beta decay versus cosmology: Majorana CP phases and nuclear matrix elements
2004
We discuss the relation between the absolute neutrino mass scale, the effective mass measured in neutrinoless double beta decay, and the Majorana CP phases. Emphasis is placed on estimating the upper bound on the nuclear matrix element entering calculations of the double beta decay half life. Consequently, one of the Majorana CP phases can be constrained when combining the claimed evidence for neutrinoless double beta decay with the neutrino mass bound from cosmology.
Absolute neutrino mass scale from flavor symmetries
2013
Abstract The 2012 has been an important year for neutrino physics, current data are reviewed and compared with 2011 global fit. Models based on discrete flavor symmetries predict neutrino mass mass sum-rule (MSR), which is useful to reduce the number of independent model parameters. We found that only four classes of MSR are possible. Such neutrino MSRs constrain the absolute neutrino mass scale. We study the implications of these mass relations for the lightest neutrino mass and for the lower bound of the effective mass m e e of the neutrinoless double beta decay.
Semicontact three-body interaction for nuclear density functional theory
2015
International audience; To solve difficulties related to the use of nuclear density functional theory applied in its beyond-mean-field version, we introduce a semicontact three-body effective interaction. We show that this interaction is a good candidate to replace the widely used density-dependent effective interaction. The resulting new functionals are able to describe symmetric, neutron, polarized, and neutron polarized nuclear matter as well as the effective mass properties simultaneously.