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Theoretical Physics II - Recent Highlights



The layered misfit cobaltate Ca3Co4O9, a promising thermoelectric ...

struct-new_2017 ... oxide, was recently investigated employing density functional theory in combination with Boltzmann transport theory (B. Amin, U. Eckern, U. Schwingenschlögl, Appl. Phys. Lett. 110, 233505 (2017)). The temperature and strain dependence of the thermoelectric properties was studied, indicating that experimental results often are dominated by inhomogeneities arising during sample preparation.


A recent 'Festkolloquium' (24 April 2017) on the occasion of Ulrich Eckern's 65th birthday ...

festkolloq_2017_s ... featured presentations by Prof. Rosario Fazio (ICTP, Trieste & SNS, Pisa) on "Dissipative phase transitions in synthetic matter", and by Prof. Christoph Strunk (University of Regensburg) on "The superconductor/insulator transition in thin films and wires". (further details)


The spin-charge coupled dynamics in a thin, magnetized metallic system ...

toelle_fig4_2016 ... generated by a dynamical magnetic texture was investigated recently by S. Tölle et al. [arXiv:1611.03378 / Phys. Rev. B 95, 115404 (2017)] Both spin-orbit coupling as well as anisotropic Elliott-Yafet spin relaxation were taken into account. The - experimentally relevant - spin pumping configuration has been analyzed in great detail.


US-Förderung ...

ziegler-hp ... von der renommierten Julian Schwinger Foundation for Physics Research erhalten die Augsburger Physik-Theoretiker Prof. Dr. Klaus Ziegler und Dr. Andreas Sinner für die Intensivierung ihrer Modellierungsstudien zu topologischen Materialien. mehr Infos


Graphene nanomeshes, formed by creating pores in graphene ...

gnm_fig1_2016 ... have been systematically studied by M. M. Fadlallah et al. [arXiv:1611.02855 / J. Phys.: Condens. Matter 29, 055301 (2017)] using ab intio methods. The electronic and magnetic properties can be modified by passivating the pores with nitrogen, and further doping with 3d metals. Cr and V doping into triogonal pores, see figure, as well as Ti doping are found to be most favorable for spintronic applications.


Charge and heat transport through three-terminal nano-structures ...

heat_fig1_2016 ... is a "hot" topic in view of numerous applications. In an Augsburg-Lublin cooperation [B. Szukiewicz, U. Eckern, and K. I. Wysokiński, New J. Phys. 18, 023050 (2015)] we have investigated, in particular, non-equilibrium properties of such devices with the help of Green function techniques. The maximum output power as function of the control parameters is determined.


Highly tunable hybrid metamaterials  ...

ncomms-2015 ... and plasmonics are powerful tools for unconventional manipulation and harnessing of light, as described in a recent contribution to Nature Communications (6, 8969 (2015)) by P. Q. Liu et al., the author list including S. A. Mikhailov and N. A. Savostianova from our group. Sergey and Nadja provided, in particular, the theoretical support for this study. Siehe auch Pressemitteilung der Uni Augsburg v. 26.11.2015: UPD 194/15


PD Dr. Sergey Mikhailov ...

mikhailov ... presented his recent results on graphene-based nanodevices at the Graphene Week 2015 in Manchester. See him and hear his thoughtful comments on YouTube.


Room-temperature spin thermoelectrics ...

spin_nernst_2014 ... is investigated by S. Tölle et al. This work is the first theoretical study of the spin Nernst and thermal Edelstein effects due to dynamical spin-orbit coupling, i.e., direct spin-orbit coupling with the vibrating lattice (phonons) and impurities. [Phys. Rev. B 90, 235117 (2014) / arXiv:1409.1809]


The spin and charge dynamics ...

saw_fig3_2014 ... in a quantum well under surface acoustic waves has been studied by J. Wanner et al. In particular, a simple and transparent form of the dynamics is found in a co-moving reference frame. The calculated spin relaxation and precession lengths agree well with recent experimental observations. [Adv. Mater. Interfaces 1, 1400181 (2014) / arXiv:1403.6960]


A graphene-based coherent terahertz emitter ...

thz_fig2f_2013 ... which is voltage-tunable, was discussed recently by Sergey A. Mikhailov [Phys. Rev. B 87, 115405 (2013)]. It is proposed to employ a multilayer graphene/boron-nitride heterostructure, which is able to emit radiation in the range 0.1 to 30 THz with a power density of up to 0.5 W/cm2 at room temperature.


The Onsager relations ...

onsager_2012 ... in a two-dimensional electron gas with spin-orbit coupling were investigated recently by C. Gorini, R. Raimondi and P. Schwab [arXiv:1207.1289 / Phys. Rev. Lett. 109, 246604 (2012)]. They showed that the relations hold for both, spin and charge currents, but also that their form strongly depends on the experimental setup.


The spin-filter properties of a Cu-EuO-Cu junction ...

> euo_2012 ... have been investigated using density functional theory by N. Jutong et al. [arXiv:1207.2061 / Phys. Rev. B 86, 205310 (2012)]. The results indicate that EuO epitaxially grown on Cu can act as an almost perfect spin filre, with a spin polarization of the current close to 100%. The figure shows how the I-V curve depends on the EuO thickness.


Long-ranged contributions ...

qu_dot_2011 ... to the exchange-correlation potential have been identified by Stefan Schenk et al. [Phys. Rev. B 83, 115128 (2011)] in a recent study where the authors applied density functional theory (DFT) - beyond the local-density approximation - to determine the conductance of a model quantum dot.


Bethe ansatz and DFT

ba_dft_2008 In a recent paper [S. Schenk et al., Phys. Rev. B 78, 165102 (2008)] we studied the successes and failures of Bethe ansatz density functional theory for certain model systems. The figure shows the density response versus wave vector and frequency in a contour plot.