Denkmalgerecht und energieeffizient sanieren: Eine Herausforderung für alle Beteiligte

Historische Quartiere und Einzeldenkmale prägen unsere Städte und Gemeinden. Daneben steht das erklärte Klimaschutzziel. Wie gelingt es, das baukulturelle Erbe zu erhalten und gleichzeitig den Anforderungen an Energieeffizienz, Wirtschaftlichkeit und Behaglichkeit Genüge zu tun, bevor Funktionsverlust und Verfall drohen? 33 Modellvorhaben in ganz Deutschland verbinden Denkmalschutz und Energieeffizienz vorbildlich

Enhanced GMR amplitude and temperature stability of copper/permalloy combination multilayers

Heitmann S, Hütten A, Hempel T, Schepper W, Reiss G. Enhanced GMR amplitude and temperature stability of copper/permalloy combination multilayers. In: Journal of Magnetism and Magnetic Materials. JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. Vol 226. ELSEVIER SCIENCE BV; 2001: 1752-1754.The high effect amplitude of {Cu/Py} multilayers at first antiferromagnetic coupling maximum (AFCM) can be combined with the temperature stability of multilayers at second AFCM by using both corresponding copper layer thicknesses in one multilayer stack. Multilayers that consist of alternating blocks of 1st and 2nd AFCM with at least two double layers each reveal the same temperature stability as multilayers at 2nd AFCM but retain higher GMR amplitude. Knowing the GMR characteristics of the multilayers at 1st and 2nd AFCM as well as of the multilayer with directly alternating copper layer thicknesses (1st, 2nd) the GMR characteristics of combination multilayers with enhanced temperature stability can be predicted. (C) 2001 Elsevier Science B.V. All rights reserved

Magnetoresistive properties of Ni(80)Fe(20/)Co1/CuAgAu/Co2 pseudo-spin-valves

Lucinski T, Hütten A, Brückl H, Hempel T, Heitmann S, Reiss G. Magnetoresistive properties of Ni(80)Fe(20/)Co1/CuAgAu/Co2 pseudo-spin-valves. In: physica status solidi (a). PHYSICA STATUS SOLIDI A-APPLIED RESEARCH. Vol 196. WILEY-V C H VERLAG GMBH; 2003: 97-100.The magnetoresistance and magnetic properties of Py/Co1/CuAgAu/Co2 have been examined. The fairly large GMR amplitude accompanied by high GMR sensitivity of about 5%/Oe was achieved. It has been shown that such high values of parameters characterizing the GMR effect could only be obtained due to the balancing effect between RKKY-like exchange coupling and magnetostatic coupling

Interplay of antiferromagnetic coupling in copper/permalloy combination multilayers

Heitmann S, Hütten A, Hempel T, Schepper W, Reiss G, Alof C. Interplay of antiferromagnetic coupling in copper/permalloy combination multilayers. In: Journal of Applied Physics. JOURNAL OF APPLIED PHYSICS. Vol 87. AMER INST PHYSICS; 2000: 4849-4851.The evolution of the giant magnetoresistance (GMR) effect in sputtered combination multilayers (CMLs) of type Py-1.8nm//{(Cu-1.8nm/Py-1.6nm)(N)/(Cu-0.9nm/Py-1.6nm)(N)}(y) with Py (permalloy=Ni81Fe19) has been investigated at room temperature. It is shown that the GMR characteristic of these CMLs can be phenomenologically predicted, if the physical properties are known, i.e., the GMR effect amplitude, double layer conductance, and bilinear and biquadratic antiferromagnetic exchange coupling constants of the two underlying {Cu/Py}(N) base systems at the first (Cu-0.9nm) and second (Cu-1.8nm) antiferromagnetic coupling maximum (AFCM). The GMR characteristic of the simplest CML with N = 1 is, e.g., determined by averaging the bilinear and biqua dratic exchange coupling constants of the two base systems. The GMR characteristics of CML with N greater than or equal to 2 are a superposition of that of the underlying {Cu/Py}(N) base systems weighted by the fraction of the corresponding double layer conductance. Furthermore, it is demonstrated that the CMLs are interesting from an application point of view since they combine the temperature stability of the underlying {Cu/Py}(N) base system at the second AFCM with a larger GMR effect amplitude. (C) 2000 American Institute of Physics. [S0021-8979(00)57908-0]

Evolution of the GMR-effect amplitude in copper/permalloy-multilayered thin films

Hütten A, Mrozek S, Heitmann S, Hempel T, Brückl H, Reiss G. Evolution of the GMR-effect amplitude in copper/permalloy-multilayered thin films. In: Acta Materialia. ACTA MATERIALIA. Vol 47. PERGAMON-ELSEVIER SCIENCE LTD; 1999: 4245-4252.The evolution of the giant magnetoresistance (GMR) effect in thin film multilayers based on {Cu/Ni81Fe19}(N) has been investigated. The maximum effect amplitude at room temperature reaches about 20% and about 10% in first and second antiferromagnetic maximum, respectively. The magnetoresistance vs field dependence does not show a hysteresis. A simple magnetization reversal model has been applied to separate contributions of bilinear and biquadratic exchange energies to the magnetic coupling. It is shown, that this model can also be used to predict saturation fields for different systems. Multilayers with Cu layer thickness corresponding to the second maximum of the antiferromagnetic coupling survive heat spikes of up to 200 degrees C retaining their sensitivity of >0.16%/Oe. Investigations of multilayers comprised of blocks of first and second antiferromagnetic coupling maximum revealed the field dependence of the coupling between these blocks and it is shown that the GMR effect is simply additive. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved

Magnetoresistance effect in asymmetric dual spin-valves - a device for three-state logic

Lucinski T, Urbaniak M, Brückl H, Hütten A, Heitmann S, Reiss G. Magnetoresistance effect in asymmetric dual spin-valves - a device for three-state logic. In: Journal of Magnetism and Magnetic Materials. JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. Vol 272. ELSEVIER SCIENCE BV; 2004: 1889-1891.We show that for asymmetric dual spin-valves MnIr/CoFe1/Cu/Py1/Cu/Py2/CoFe2/MnIr (Py denotes Ni80Fe20 Permalloy alloy), the application of two different ferromagnetic materials as pinned layers can result in appearance of three well-separated stages in giant magnetoresistance (GMR) effect reflecting three different and almost independent magnetization reversal processes. For the correct choice of the constituent layer thicknesses, the GMR amplitude of the dual spin-valve can depend on the field sweep direction. (C) 2003 Elsevier B.V. All rights reserved

Magnetoresistance study of Ni80Fe20/Co1/CuAgAu/Co2 asymmetric sandwiches

Lucinski T, Hütten A, Brückl H, Heitmann S, Hempel T, Reiss G. Magnetoresistance study of Ni80Fe20/Co1/CuAgAu/Co2 asymmetric sandwiches. JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. 2004;269(1):78-88.The (Ni(80)Fe(20i)Col);CuAgAu/Co2 asymmetric sandwiches have been examined for different sublayer thicknesses. Magnetoresistance, magnetooptical Kerr effect and alternating gradient magnetometry measurements showed that for 1.2 nm less than or equal to d(CuAgAu) less than or equal to 1.6 nm our trilayers are antiferromagneticatly coupled whereas for d(CuAgAu) greater than or equal to 1.9 nm the coupling between Ni80Fe20i Col and Co2 is ferromagnetic. The ferromagnetic coupling strength oscillates with CuAgAu thickness with a period of 1 nm. The appearance of the ferromagnetic interlayer coupling for d(CuAgAu) greater than or equal to 1.9 nm and its oscillatory character result from the interplay between RKKY-Iike exchange coupling and the magnetostatic orange-peel coupling. The values of the ferromagnetic coupling field between Ni80Fe20iCoI and Co2 for a constant CuAgAu thickness can be either enhanced or reduced depending on the ratio between Col, Co2 and Ni80Fe20 thicknesses. In spite of oscillatory ferromagnetic coupling strength for d(CuAgAu) greater than or equal to 1.9 nm our trilayers show the GMR amplitude of about 10% and the GMR field sensitivity of about 5%/Oe at room temperature being very promising from the application point of view. (C) 2003 Elsevier B.V. All rights reserved

Magnetic and mossbauer study of Fe/Si multilayers

Lucinski T, Kopcewicz M, Hütten A, et al. Magnetic and mossbauer study of Fe/Si multilayers. In: Journal of Applied Physics. JOURNAL OF APPLIED PHYSICS. Vol 93. AMER INST PHYSICS; 2003: 6501-6503.The magnetic and structural properties of Fe/Si multilayers (Mls) have been studied by x-ray diffraction (XRD) and conversion electron Mossbauer spectroscopy (CEMS) methods. Strong antiferromagnetic (AF) coupling J=-1.93 mJ/m(2) accompanied by saturation field of 1.5 T has been found for Si layer thickness d(Si)=1.4 nm. Magnetic moment measurements of Fe/Si Mls vs Fe thickness revealed that 0.25 nm of Fe per single interface is magnetically inactive. The CEMS spectra recorded at room temperature consist of the Zeeman sextet characteristic of the pure Fe phase (hyperfine field of about 32.8 T) accompanied by two spectral components related to FeSi system: magnetic broad sextet and a quadrupole doublet. The broad sextet could originate from various Fe sites at the interface. The nonmagnetic quadrupole split (QS) doublet is most probably associated with the nonstoichiometric c-Fe1-xSix phase. For larger Si layer thickness (d(Si)>2 nm) the spectral contribution of the QS doublet increases from 5.7% to about 16%. (C) 2003 American Institute of Physics

Magnetic properties of Fe/Si and Co/Si multilayers

Lucinski T, Kopcewicz M, Hütten A, et al. Magnetic properties of Fe/Si and Co/Si multilayers. MATERIALS SCIENCE-POLAND. 2003;21(1):25-37.Magnetic and structural properties of Fe/Si, Fe/Fe33Si66 and Co/Si multilayers have been studied. Very strong AF coupling J=-1.93 mJ/m(2) accompanied by saturation field of 1.5 T has been found for d(Si) = 1.4 nm. The CEMS spectra recorded at room temperature consist of the Zeeman sextet characteristic of the pure Fe phase accompanied by two spectral components related to FeSi system: magnetic broad sextet and a quadrupole doublet. The broad sextet could originate from various Fe sites at the interface. The nonmagnetic QS doublet is most probably associated with the nonstoichiometric c-Fe1-xSix phase. Comparing the results obtained for Fe/Si and Fe/Fe33Si66 multilayers we conclude that the exchange coupling is distinctly stronger for nominally pure spacer layer. For Co/Si multilayers a very weak antiferromagnetic coupling and oscillatory F-AF(d(Si)) behaviour was observed, most probably due to the formation of Co-Si nonmagnetic metallic phases replacing the nominally pure Si spacer layers. We have shown that AF coupled Fe/Si multilayers can be successfully applied as an antiferromagnets in the magnetoresistive (Fe/Si)(15)/Fe/Col/Cu/Co2 system