Dipolar spin-misalignment correlations in inhomogeneous magnets: Comparison between neutron scattering and micromagnetic

in Physical Review. B, Condensed Matter (2015), 92(1), 014427

In inhomogeneous bulk ferromagnets, the dominating sources of spin disorder are related to spatial variations of (i) the magnitude of the local saturation magnetization and of (ii) the magnitude and/or ... [more ▼]

In inhomogeneous bulk ferromagnets, the dominating sources of spin disorder are related to spatial variations of (i) the magnitude of the local saturation magnetization and of (ii) the magnitude and/or direction of the magnetic anisotropy field. For the particular example of a porous ferromagnet, where the magnetization inhomogeneity is at maximum, we demonstrate, by means of experimental neutron scattering data and micromagnetic simulations, the anisotropic character of magnetization fluctuations induced by the dipolar interaction. [less ▲]

F center in lithium fluoride revisited: Comparison of solid-state physics and quantum-chemistry approaches

in Physical Review. B, Condensed Matter (2014), 89

We revisit the theoretical description of the F color center in lithium fluoride employing advanced complementary ab initio techniques.We compare the results from periodic supercell calculations involving ... [more ▼]

We revisit the theoretical description of the F color center in lithium fluoride employing advanced complementary ab initio techniques.We compare the results from periodic supercell calculations involving density-functional theory (DFT) and post-DFT techniques with those from the embedded-cluster approach involving quantumchemical many-electron wave-function techniques. These alternative approaches yield results in good agreement with each other and with the experimental data provided that correlation effects are properly taken into account. [less ▲]

Effective fluctuation theorems for electron transport in a double quantum dot coupled to a quantum point contact

in Physical Review. B, Condensed Matter (2013), 88(115134),

A theoretical study is reported of electron transport at finite temperature in a double quantum dot (DQD) capacitively coupled to a quantum point contact (QPC) for the measurement of the DQD charge state ... [more ▼]

A theoretical study is reported of electron transport at finite temperature in a double quantum dot (DQD) capacitively coupled to a quantum point contact (QPC) for the measurement of the DQD charge state. Starting from a Hamiltonian model, a master equation is obtained for the stochastic process taking place in the DQD while the QPC is at or away from equilibrium, allowing us to study the measurement back-action of the QPC onto the DQD. The QPC is treated nonperturbatively in our analysis. Effective fluctuation theorems are established for the full counting statistics of the DQD current under different limiting conditions. These fluctuation theorems hold with respect to an effective affinity characterizing the nonequilibrium environment of the DQD and differing from the applied voltage if the QPC is out of equilibrium. The effective affinity may even change its sign if the Coulomb drag of the QPC reverses the DQD current. The thermodynamic implications of the effective fluctuation theorems are discussed. [less ▲]

Fluctuation theorems for capacitively coupled electronic currents

in Physical Review. B, Condensed Matter (2011)

The counting statistics of electron transport is studied theoretically in a system with two capacitively coupled parallel transport channels. Each channel is composed of a quantum dot connected by ... [more ▼]

The counting statistics of electron transport is studied theoretically in a system with two capacitively coupled parallel transport channels. Each channel is composed of a quantum dot connected by tunneling to two reservoirs. The nonequilibrium steady state of the system is controlled by two affinities or thermodynamic forces, each one determined by the two reservoirs of each channel. The status of a single-current fluctuation theorem is investigated starting from the fundamental two-current fluctuation theorem, which is a consequence of microreversibility. We show that the single-current fluctuation theorem holds in the limit of a large Coulomb repulsion between the two parallel quantum dots, as well as in the limit of a large current ratio between the parallel channels. In this latter limit, the symmetry relation of the single-current fluctuation theorem is satisfied with respect to an effective affinity that is much lower than the affinity determined by the reservoirs. This backaction effect is characterized quantitatively. [less ▲]

Oscillations in the magnetoconductance autocorrelation function for ballistic microstructures

in Physical Review. B, Condensed Matter (1998), 57(16), 9875-9878

We present a comparison between experiment and theory for the magnetoconductance autocorrelation function C(Delta B) for transport through a stadium-shaped ballistic microstructure. The correlation ... [more ▼]

We present a comparison between experiment and theory for the magnetoconductance autocorrelation function C(Delta B) for transport through a stadium-shaped ballistic microstructure. The correlation function displays damped oscillations which can be traced to the quantum interference between bundles of short trajectories. We present two different semiclassical calculations applicable for large and small mode numbers of the quantum wire, respectively. Good agreement is found with experimental data taken at relatively low mode numbers. [S0163-1829(98)03316-5]. [less ▲]