News (7 Feb 2016 - 7 Jan 2017)

Interplay between correlation effects and electron pairing

added on 7 January 2017, 10:55

T. Domański et al. studied subgap spectrum of the interacting single-level quantum dot coupled between two superconducting reservoirs, forming the Josephson-type circuit, and additionally hybridized with a metallic normal lead. They quantitatively establish the phase-dependent Kondo temperature and show that it can be read off from the half-width of the zero-bias enhancement in the Andreev conductance in the doublet phase.

Stoner versus Heisenberg

added on 7 January 2017, 10:45

E. Turgut et al. use ultrafast high harmonics to measure time-, energy-, and angle-resolved M-edge magnetic asymmetry spectra for Co films after optical pumping to induce ultrafast demagnetization. They found that the magnon contribution to ultrafast demagnetization is already strong on subpicosecond time scales, while the reduction in exchange splitting persists to several picoseconds.

Noisy metamolecule

added on 18 December 2016, 18:50

T. Chlouba, M. Žonda, and T. Novotný published a comment on recent Letter by Andrianov et al. Using sparse numerical solvers they shown that some of the results in the original letter are incorrect, most likely due to insufficient Monte Carlo sampling. These findings call for a corrected interpretation of the physical behavior of the studied model.

Measurement of the spin penetration length using second-harmonic voltage

added on 16 October 2016, 16:47

A theoretical description of spin current injection from a nonmagnetic layer into a magnetic one is presented by P. Baláž et al. The authors propose a novel method of measurement the transverse spin penetration length in magnetic metals based on second harmonic voltage measurement.

Ab initio theory of laser-induced magnetization in metals

added on 15 October 2016, 16:37

M. Berritta, R. Mondal, K. Carva, and P. M. Oppeneer present in Physical Review Letters a first material specific theory of the magnetization induced by circularly polarized laser light in metals. They show that the inverse Faraday effect leads to the existence of both spin and orbital induced magnetizations which exhibit a surprisingly different behaviour.

Quantum dot attached to superconducting leads

added on 15 October 2016, 16:26

Spin-symmetric solution of an interacting quantum dot attached to superconducting leads is presented by V. Janiš, V. Pokorný, and M. Žonda. They shown that under certain conditions the spin-symmetric solution becomes degenerate.

Exchange and spin-orbit induced phenomena in (Ga,Mn)As

added on 15 October 2016, 16:00

Physical properties induced by exchange interactions and spin-orbit coupling in the diluted (Ga,Mn)As ferromagnetic semiconductor are studied from first principles by J. Kudrnovský, V. Drchal, and I. Turek. Their calculations based on recently developed Kubo-Bastin transport theory. Good agreement of calculated physical quantities with experiment was obtained.

Electronic transport in Bi2Te3

added on 16 August 2016, 9:00

K. Carva et al. published a first-principles study of the electronic, magnetic, and transport properties of the 3D topological insulator Bi2Te3 doped with Mn atoms in substitutional and interstitial van der Waals gap positions. Their calculations indicate that for explanation of experimental observations the role of interstitials may be more important than expected.

The paper was selected for Phys. Rev. B Kaleidoscope in June 2016.

Perturbation theory for an Anderson QD

added on 7 February 2016, 15:43

Anderson quantum dot was studied by M. Žonda et al. by means of perturbation expansion to the second order. They suggest that in some cases the heavy numerical tools such as numerical renormalization group or quantum Monte Carlo can be safely replaced by a perturbative approach with less computational demands.

Quantum Mechanics I.

added on 7 February 2016, 13:03

First part of a new textbook by J. Klíma and B. Velický on quantum mechanics in Czech language will appear soon. The book is an introduction to nonrelativistic quantum mechanics supported by number of examples.

source: Karolinum