arXiv subjects

D. Grundler

Publications and source records attributed to D. Grundler.

22 records · Page 2Linked to original sources

arXiv2013

Enhanced quantum oscillatory magnetization and non-equilibrium currents in an interacting two-dimensional electron system in MgZnO/ZnO with repulsive scatterers

Torque magnetometry at low temperature and in high magnetic fields B is performed on a MgZnO/ZnO heterostructure incorporating a high-mobility two-dimensional electron system. We find a sawtooth-like quantum oscillatory magnetization M(B), i.e., the de Haas-van Alphen (dHvA) effect. At the same time, unexpected spike-like overshoots in M and non-equilibrium currents are observed which allow us to identify the microscopic nature and density of the residual disorder. The acceptor-like scatterers give rise to a magnetic thaw down effect which enhances the dHvA amplitude beyond the electron-electron interaction effects being present in the MgZnO/ZnO heterostructure

cond-mat.mes-hall↗

arXiv2013

Nanoscale multifunctional sensor formed by a Ni nanotube and a scanning Nb nanoSQUID

Nanoscale magnets might form the building blocks of next generation memories. To explore their functionality, magnetic sensing at the nanoscale is key. We present a multifunctional combination of a scanning nanometer-sized superconducting quantum interference device (nanoSQUID) and a Ni nanotube attached to an ultrasoft cantilever as a magnetic tip. We map out and analyze the magnetic coupling between the Ni tube and the Nb nanoSQUID, demonstrate imaging of an Abrikosov vortex trapped in the SQUID structure - which is important in ruling out spurious magnetic signals - and reveal the high potential of the nanoSQUID as an ultrasensitive displacement detector. Our results open a new avenue for fundamental studies of nanoscale magnetism and superconductivity.

cond-mat.supr-con↗

arXiv2003

Optimization of the extraordinary magnetoresistance in semiconductor-metal hybrid structures for magnetic-field sensor applications

Semiconductor-metal hybrid structures can exhibit a very large geometrical magnetoresistance effect, the so-called extraordinary magnetoresistance (EMR) effect. In this paper, we analyze this effect by means of a model based on the finite element method and compare our results with experimental data. In particular, we investigate the important effect of the contact resistance $ρ_c$ between the semiconductor and the metal on the EMR effect. Introducing a realistic $ρ_c=3.5\times 10^{-7} Ω{\rm cm}^2$ in our model we find that at room temperature this reduces the EMR by 30% if compared to an analysis where $ρ_c$ is not considered.

cond-mat.mes-hall↗

arXiv2002

Ballistic Spin Injection from Fe(001) into ZnSe and GaAs

We consider the spin injection from Fe into ZnSe and GaAs in the ballistic limit. By means of the ab initio SKKR method we calculate the ground state properties of epitaxial Fe|ZnSe(001) and Fe|GaAs(001) heterostructures. Three injection processes are considered: injection of hot electrons and injection of "thermal" electrons with and without an interface barrier. The calculation of the conductance by the Landauer formula shows, that these interfaces act like a nearly ideal spin filter, with spin polarization as high as 99%. This can be traced back to the symmetry of the band structure of Fe for normal incidence.

cond-mat↗