Helmut Schultheiss
Helmholtz-Zentrum Dresden-Rossendorf
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Featured researches published by Helmut Schultheiss.
Nature Communications | 2014
K. Vogt; F.Y. Fradin; J. Pearson; T. Sebastian; S. D. Bader; B. Hillebrands; A. Hoffmann; Helmut Schultheiss
Recent developments in the field of spin dynamics--like the interaction of charge and heat currents with magnons, the quasi-particles of spin waves--opens the perspective for novel information processing concepts and potential applications purely based on magnons without the need of charge transport. The challenges related to the realization of advanced concepts are the spin-wave transport in two-dimensional structures and the transfer of existing demonstrators to the micro- or even nanoscale. Here we present the experimental realization of a microstructured spin-wave multiplexer as a fundamental building block of a magnon-based logic. Our concept relies on the generation of local Oersted fields to control the magnetization configuration as well as the spin-wave dispersion relation to steer the spin-wave propagation in a Y-shaped structure. Thus, the present work illustrates unique features of magnonic transport as well as their possible utilization for potential technical applications.
Applied Physics Letters | 2012
Yiyan Sun; Young-Yeal Song; Houchen Chang; Michael Kabatek; Michael Jantz; William Schneider; Mingzhong Wu; Helmut Schultheiss; A. Hoffmann
Growth of nm-thick yttrium iron garnet films and ferromagnetic resonance (FMR) linewidth properties in the films are reported. The films were grown on gadolinium gallium garnet substrates by pulsed laser deposition (PLD). Films in the 5–35 nm thickness range showed a (111) orientation and a surface roughness between 0.1 and 0.3 nm. The 10 nm films showed a 10 GHz FMR linewidth of about 6 Oe and a damping constant of 3.2 × 10−4. The FMR linewidth increases with both the surface roughness and the surface Fe deficiency. Thicker films exhibit a smaller FMR linewidth and a lower damping constant.
Applied Physics Letters | 2009
A. V. Chumak; P. Pirro; A. A. Serga; Mikhail Kostylev; R. L. Stamps; Helmut Schultheiss; K. Vogt; S. J. Hermsdoerfer; B. Laegel; P. A. Beck; B. Hillebrands
Transmission of microwave spin waves through a microstructured magnonic crystal in the form of a Permalloy waveguide of a periodically varying width was studied experimentally and theoretically. The spin wave characteristics were measured by spatially resolved Brillouin light scattering microscopy. A rejection frequency band was clearly observed. The band gap frequency was controlled by the applied magnetic field. The measured spin-wave intensity as a function of frequency and propagation distance is in good agreement with a model calculation.
Applied Physics Letters | 2012
K. Vogt; Helmut Schultheiss; Shikha Jain; J. Pearson; A. Hoffmann; S. D. Bader; B. Hillebrands
We studied the propagation of spin waves in a Ni81Fe19 micro-waveguide comprising a smooth, S-shaped bend using Brillouin light scattering microscopy. A direct current flowing through a gold wire underneath the Ni81Fe19 provides a local magnetic field, which maintains a transverse magnetization around the bend of the waveguide. It is demonstrated that spin-wave propagation inside the bend can be realized in contrast to the case of an externally applied magnetic field, which generates strong inhomogeneities in the internal effective field distribution, preventing any spin-wave propagation across the bend.
Applied Physics Letters | 2009
Dong-Soo Han; Sang-Koog Kim; Jun-Young Lee; S. J. Hermsdoerfer; Helmut Schultheiss; B. Leven; B. Hillebrands
We found by micromagnetic simulations that the motion of a transverse wall (TW)–type domain wall in magnetic thin-film nanostripes can be manipulated via interaction with spin waves (SWs) propagating through the TW. The velocity of the TW motion can be controlled by changes of the frequency and amplitude of the propagating SWs. Moreover, the TW motion is efficiently driven by specific SW frequencies that coincide with the resonant frequencies of the local modes existing inside the TW structure. The use of propagating SWs, whose frequencies are tuned to those of the intrinsic TW modes, is an alternative approach for controlling TW motion in nanostripes.
Frontiers of Physics in China | 2015
T. Sebastian; Katrin Schultheiss; Björn Obry; B. Hillebrands; Helmut Schultheiss
Spin waves constitute an important part of research in the field of magnetization dynamics. Spin waves are the elementary excitations of the spin system in a magnetically ordered material state and magnons are their quasi particles. In the following article, we will discuss the optical method of Brillouin light scattering (BLS) spectroscopy which is a now a well established tool for the characterization of spin waves. BLS is the inelastic scattering of light from spin waves and confers several benefits: the ability to map the spin wave intensity distribution with spatial resolution and high sensitivity as well as the potential to simultaneously measure the frequency and the wave vector and, therefore, the dispersion properties. For several decades, the field of spin waves gained huge interest by the scientific community due to its relevance regarding fundamental issues of spindynamics in the field of solid states physics. The ongoing research in recent years has put emphasis on the high potential of spin waves regarding information technology. In the emerging field of \textit{magnonics}, several concepts for a spin-wave based logic have been proposed and realized. Opposed to charge-based schemes in conventional electronics and spintronics, magnons are charge-free currents of angular momentum, and, therefore, less subject to scattering processes that lead to heating and dissipation. This fact is highlighted by the possibility to utilize spin waves as information carriers in electrically insulating materials. These developments have propelled the quest for ways and mechanisms to guide and manipulate spin-wave transport. In particular, a lot of effort is put into the miniaturization of spin-wave waveguides and the excitation of spin waves in structures with sub-micrometer dimensions. For the further development of potential spin-wave-based devices, the ability to directly observe spin-wave propagation with spatial resolution is crucial. As an optical technique BLS do
Applied Physics Letters | 2009
K. Vogt; Helmut Schultheiss; S. J. Hermsdoerfer; P. Pirro; A. A. Serga; B. Hillebrands
We present the determination of the wavelength and phase of propagating spin waves in magnetic microstructures made of Ni81Fe19 using the shorted end of a coplanar waveguide for local excitation. The spin wave characteristics have been measured by phase resolved Brillouin light scattering microscopy. This recently developed technique allows for the unambiguous experimental visualization of the phase structure of propagating spin waves and is employed here to magnetic microstructures. The results show an excellent agreement with the theoretically predicted spin-wave dispersion relations.
Physica Status Solidi B-basic Solid State Physics | 2011
P. Pirro; T. Brächer; K. Vogt; Björn Obry; Helmut Schultheiss; B. Leven; B. Hillebrands
We present experimental observations of the interference of spin-wave modes propagating in opposite directions in micron-sized Ni81Fe19-waveguides. To monitor the local spin-wave intensity distribution and phase of the formed interference pattern, we use Brillouin light scattering microscopy. The two-dimensional spin-wave intensity map can be understood by considering the interference of several waveguide eigenmodes with different wavevectors quantized across the width of the stripe. The phase shows a transition from linear dependence on the space coordinate near the antennas characteristic for propagating waves to discrete values in the center region characteristic for standing waves.
Applied Physics Letters | 2011
Matthias B. Jungfleisch; A. V. Chumak; Vitaliy I. Vasyuchka; A. A. Serga; Björn Obry; Helmut Schultheiss; P. A. Beck; Alexy Davison Karenowska; Eiji Saitoh; B. Hillebrands
It is demonstrated that the temporal evolution of a spin-wave induced inverse spin Hall effect voltage in a magnetic insulator–nonmagnetic metal structure is distinctly different from that of the directly excited (microwave pulse driven) spin-wave mode from which it originates. The differences in temporal behavior provide compelling evidence that incoherent secondary spin-wave modes, having a range of different characteristic lifetimes, make an important contribution to spin pumping at the insulator-metal interface.
Applied Physics Letters | 2011
P. Clausen; K. Vogt; Helmut Schultheiss; S. Schäfer; Björn Obry; Georg Wolf; P. Pirro; B. Leven; B. Hillebrands
We study spin-wave transport in a microstructured Ni81Fe19 waveguide exhibiting broken translational symmetry. We observe the conversion of a beam profile composed of symmetric spin-wave width modes with odd numbers of antinodes n = 1, 3,… into a mixed set of symmetric and asymmetric modes. Due to the spatial homogeneity of the exciting field along the used microstrip antenna, quantized spin-wave modes with an even number n of antinodes across the stripe’s width cannot be directly excited. We show that a break in translational symmetry may result in a partial conversion of even spin-wave waveguide modes.