@inproceedings{HolthausHagedornKlanketal., author = {Holthaus, Carsten and Hagedorn, Oliver and Klank, Michael and Shamonin (Chamonine), Mikhail and Trifonov, A. and D{\"o}tsch, Horst}, title = {Preparation and Characterization of Sensitive Magnetic Garnet Films for MOI Applications}, series = {Magneto-Optical Imaging. Proceedings of the NATO Advanced Research Workshop on Magneto-Optical Imaging, {\O}ystese, Norway, 28 - 30 August 2003}, booktitle = {Magneto-Optical Imaging. Proceedings of the NATO Advanced Research Workshop on Magneto-Optical Imaging, {\O}ystese, Norway, 28 - 30 August 2003}, publisher = {Kluwer}, address = {Dodrecht}, doi = {10.1007/978-94-007-1007-8_42}, pages = {329 -- 336}, abstract = {Magnetic garnet films prepared by liquid phase epitaxy on paramagnetic substrates of gadolinium gallium garnet are currently used for the imaging of magnetic field distributions. This application is based on the Faraday rotation which can be strongly enhanced by bismuth incorporation. For gray scale imaging the plane of the sensor film should be an easy plane of magnetization so that no domains nucleate. However, incorporation of bismuth induces a strong positive uniaxial anisotropy perpendicular to the film plane, especially if films of [111] orientation are used. To counteract this unwanted behavior neodymium and/or praseodymium are substituted in addition to bismuth. These two elements cause a very strong negative anisotropy. This is tested experimentally by growing series of garnet films with gradually changing composition and growth parameters.}, language = {en} } @article{BodnarukBrunhuberKalitaetal., author = {Bodnaruk, Andrii V. and Brunhuber, Alexander and Kalita, Viktor M. and Kulyk, Mykola M. and Snarskii, Andrei A. and Lozenko, Albert F. and Ryabchenko, Sergey M. and Shamonin (Chamonine), Mikhail}, title = {Temperature-dependent magnetic properties of a magnetoactive elastomer: Immobilization of the soft-magnetic filler}, series = {Journal of Applied Physics}, volume = {123}, journal = {Journal of Applied Physics}, number = {11}, publisher = {AIP Publishing}, doi = {10.1063/1.5023891}, abstract = {The magnetic properties of a magnetoactive elastomer (MAE) filled with mu m-sized soft-magnetic iron particles have been experimentally studied in the temperature range between 150 K and 310 K. By changing the temperature, the elastic modulus of the elastomer matrix was modified, and it was possible to obtain magnetization curves for an invariable arrangement of particles in the sample and in the case when the particles were able to change their position within the MAE under the influence of magnetic forces. At low (less than 220 K) temperatures, when the matrix becomes rigid, the magnetization of the MAE does not show a hysteresis behavior, and it is characterized by a negative value of the Rayleigh constant. At room temperature, when the polymer matrix is compliant, a magnetic hysteresis exists where the dependence of the differential magnetic susceptibility on the magnetic field exhibits local maxima. The appearance of these maxima is explained by the elastic resistance of the matrix to the displacement of particles under the action of magnetic forces.}, language = {en} } @misc{ScharfenbergMottokArtmannetal., author = {Scharfenberg, Georg and Mottok, J{\"u}rgen and Artmann, Christina and Hobelsberger, Martin and Paric, Ivan and Großmann, Benjamin and Pohlt, Clemens and Wackerbarth, Alena and Pausch, Uli and Heidrich, Christiane and Fadanelli, Martin and Elsner, Michael and P{\"o}cher, Daniel and Pittroff, Lenz and Beer, Stefan and Br{\"u}ckl, Oliver and Haslbeck, Matthias and Sterner, Michael and Thema, Martin and Muggenthaler, Nicole and Lenck, Thorsten and G{\"o}tz, Philipp and Eckert, Fabian and Deubzer, Michael and Stingl, Armin and Simsek, Erol and Kr{\"a}mer, Stefan and Großmann, Benjamin and Schlegl, Thomas and Niedersteiner, Sascha and Berlehner, Thomas and Joblin, Mitchell and Mauerer, Wolfgang and Apel, Sven and Siegmund, Janet and Riehle, Dirk and Weber, Joachim and Palm, Christoph and Zobel, Martin and Al-Falouji, Ghassan and Prestel, Dietmar and Scharfenberg, Georg and Mandl, Roland and Deinzer, Arnulf and Halang, W. and Margraf-Stiksrud, Jutta and Sick, Bernhard and Deinzer, Renate and Scherzinger, Stefanie and Klettke, Meike and St{\"o}rl, Uta and Wiech, Katharina and Kubata, Christoph and Sindersberger, Dirk and Monkman, Gareth J. and Dollinger, Markus and Dembianny, Sven and K{\"o}lbl, Andreas and Welker, Franz and Meier, Matthias and Thumann, Philipp and Swidergal, Krzysztof and Wagner, Marcus and Haug, Sonja and Vernim, Matthias and Seidenst{\"u}cker, Barbara and Weber, Karsten and Arsan, Christian and Schone, Reinhold and M{\"u}nder, Johannes and Schroll-Decker, Irmgard and Dillinger, Andrea Elisabeth and Fuchshofer, Rudolf and Monkman, Gareth J. and Shamonin (Chamonine), Mikhail and Geith, Markus A. and Koch, Fabian and {\"U}hlin, Christian and Schratzenstaller, Thomas and Saßmannshausen, Sean Patrick and Auchter, Eberhard and Kriz, Willy and Springer, Othmar and Thumann, Maria and Kusterle, Wolfgang and Obermeier, Andreas and Udalzow, Anton and Schmailzl, Anton and Hierl, Stefan and Langer, Christoph and Schreiner, Rupert}, title = {Forschungsbericht 2015}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-00-048589-3}, doi = {10.35096/othr/pub-1386}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13867}, language = {de} } @article{ShamoninChamonineKlankHagedornetal., author = {Shamonin (Chamonine), Mikhail and Klank, Michael and Hagedorn, Oliver and D{\"o}tsch, Horst}, title = {Magneto-optical visualization of metal-loss defects in a ferromagnetic plate: experimental verification of theoretical modeling}, series = {Applied optics}, volume = {40}, journal = {Applied optics}, number = {19}, publisher = {Optica Publishing Group}, doi = {10.1364/ao.40.003182}, pages = {3182 -- 3189}, abstract = {Rare-earth iron garnet films with in-plane magnetic anisotropy grown on [111]-oriented substrates are promising for the visualization of magnetic leakage fields in nondestructive evaluation. Such magneto-optical films have to be specifically engineered, and we give an example of this technology. To assess the validity and accuracy of finite-element calculations of a magnetization assembly combined with the physical modeling of the image formation, comparisons between calculated and experimentally obtained magneto-optical images of metal-loss defects have been made. A convincing quantitative agreement is demonstrated. It is shown that both physical and computer modeling techniques allow for a predictive engineering design of the prospective applications and provide greater insight into the method.}, language = {en} } @article{BodnarukAndriiVBrunhuberetal., author = {Bodnaruk, and Andrii V., and Brunhuber, Alexander and Kalita, Viktor M. and Kulyk, Mykola M. and Kurzweil, Peter and Snarskii, Andrei A. and Lozenko, Albert F. and Ryabchenko, Sergey M. and Shamonin (Chamonine), Mikhail}, title = {Magnetic anisotropy in magnetoactive elastomers, enabled by matrix elasticity}, series = {Polymer}, volume = {162}, journal = {Polymer}, number = {January}, publisher = {Elsevier}, doi = {10.1016/j.polymer.2018.12.027}, pages = {63 -- 72}, abstract = {Polydimethylsiloxane based magnetoactive elastomers demonstrate above the melting transition range (e.g. at room temperature) an induced uniaxial magnetic anisotropy, which grows with increasing magnetic field. By freezing a material down to 150 K, displaced iron microparticles are immobilized, so that the magnetic anisotropy can be measured. Magnetic anisotropy "constant" is a consequence of particle displacements and a characteristic of the energy of internal deformations in the polymer matrix. The maximum anisotropy constant of the filling is at least one order of magnitude larger than the shear modulus of the pure elastomer (matrix). In a magnetic field, the gain in the rigidity of the composite material is attributed to the magnetomechanical coupling, which is in turn a source of anisotropy. The concept of effective magnetic field felt by the magnetization allows one to explain the magnetization curve at room temperature from low-temperature measurements. The results can be useful for developing vibration absorbers and isolators.}, language = {en} } @inproceedings{DoetschKlankHagedornetal., author = {D{\"o}tsch, Horst and Klank, Michael and Hagedorn, Oliver and Holthaus, Carsten and Shamonin (Chamonine), Mikhail and Trifonov, A.}, title = {Optimization of Magnetic Garnet Films for Magneto-Optical Imaging of Magnetic Field Distributions}, series = {Magneto-Optical Imaging. Proceedings of the NATO Advanced Research Workshop on Magneto-Optical Imaging, {\O}ystese, Norway, 28 - 30 August 2003}, booktitle = {Magneto-Optical Imaging. Proceedings of the NATO Advanced Research Workshop on Magneto-Optical Imaging, {\O}ystese, Norway, 28 - 30 August 2003}, publisher = {KLuwer}, address = {Dodrecht}, doi = {10.1007/978-94-007-1007-8_39}, pages = {301 -- 309}, abstract = {Rare-earth iron garnet films are currently applied for magneto-optical imaging of magnetic field distributions. The physical properties of the films can be controlled by the chemical composition, the growth conditions and the crystallographic orientation. The sensor properties must be optimized according to the application desired. A new optimization method is introduced based on the swing of the photoresponse. An application example is presented. Furthermore, the sensitivity can be strongly enhanced using specific crystallographic orientations which induce an easy plane of magnetization being tilted with respect to the film plane. Experimental results of a [112] oriented garnet film are in good agreement with calculations. The influence of the cubic anisotropy on the sensor performance is discussed. Finally, it is shown that also domain films can be applied for magneto-optical imaging.}, language = {en} } @article{KlankHagedornHolthausetal., author = {Klank, Michael and Hagedorn, Oliver and Holthaus, Carsten and Shamonin (Chamonine), Mikhail and D{\"o}tsch, Horst}, title = {Characterization and optimization of magnetic garnet films for magneto-optical visualization of magnetic field distributions}, series = {NDT \& E International}, volume = {36}, journal = {NDT \& E International}, number = {6}, publisher = {Elsevier}, doi = {10.1016/S0963-8695(03)00012-4}, pages = {375 -- 381}, abstract = {Rare-earth iron garnet films with in-plane anisotropy grown on (111)-oriented substrates can be used as magneto-optical indicator films for visualization of magnetic leakage fields in nondestructive evaluation. The influence of Faraday rotation, Faraday ellipticity, absorption and film thickness on the performance of a magneto-optical indicator film is investigated. A new optimization method is introduced and compared with the method of contrast optimization. The theory is experimentally verified and an application example is presented.}, language = {en} } @article{KrieglKravanjaHribaretal., author = {Kriegl, Raphael and Kravanja, Gaia and Hribar, Luka and Čoga, Lucija and Drevenšek-Olenik, Irena and Jezeršek, Matija and Kalin, Mitjan and Shamonin (Chamonine), Mikhail}, title = {Microstructured Magnetoactive Elastomers for Switchable Wettability}, series = {Polymers}, volume = {14}, journal = {Polymers}, number = {18}, publisher = {MDPI}, doi = {10.3390/polym14183883}, pages = {1 -- 21}, abstract = {We demonstrate the control of wettability of non-structured and microstructured magnetoactive elastomers (MAEs) by magnetic field. The synthesized composite materials have a concentration of carbonyl iron particles of 75 wt.\% (≈27 vol.\%) and three different stiffnesses of the elastomer matrix. A new method of fabrication of MAE coatings on plastic substrates is presented, which allows one to enhance the response of the apparent contact angle to the magnetic field by exposing the particle-enriched side of MAEs to water. A magnetic field is not applied during crosslinking. The highest variation of the contact angle from (113 ± 1)° in zero field up to (156 ± 2)° at about 400 mT is achieved in the MAE sample with the softest matrix. Several lamellar and pillared MAE structures are fabricated by laser micromachining. The lateral dimension of surface structures is about 50 µm and the depth varies between 3 µm and 60 µm. A systematic investigation of the effects of parameters of laser processing (laser power and the number of passages of the laser beam) on the wetting behavior of these structures in the absence and presence of a magnetic field is performed. In particular, strong anisotropy of the wetting behavior of lamellar structures is observed. The results are qualitatively discussed in the framework of the Wenzel and Cassie-Baxter models. Finally, directions of further research on magnetically controlled wettability of microstructured MAE surfaces are outlined. The obtained results may be useful for the development of magnetically controlled smart surfaces for droplet-based microfluidics.}, language = {en} } @article{ShamoninChamonineBeukerRosenetal., author = {Shamonin (Chamonine), Mikhail and Beuker, T. and Rosen, P. and Klank, Michael and Hagedorn, Oliver and D{\"o}tsch, Horst}, title = {Feasibility of magneto-optic flaw visualization using thin garnet films}, series = {NDT \& E International}, volume = {33}, journal = {NDT \& E International}, number = {8}, publisher = {Elsevier}, doi = {10.1016/s0963-8695(00)00028-1}, pages = {547 -- 553}, abstract = {We investigate the feasibility of using rare-earth iron garnet films grown on (111)-oriented substrates as magneto-optic indicator films for the visualization of magnetic leakage fields in non-destructive evaluation. In most cases the leakage field of the defect has a strong component in the film plane. The influence of this in-plane dc magnetic field on the image formation is investigated. It is shown that the presence of a strong in-plane magnetic field allows one to extend the dynamic range of the out-of-plane field imposed by the uniaxial anisotropy field HA. On the other hand, an in-plane field reduces the sensitivity. The guidelines for selecting parameters of magneto-optic indicator films are given.}, language = {en} } @article{KlankHagedornShamoninChamonineetal., author = {Klank, Michael and Hagedorn, Oliver and Shamonin (Chamonine), Mikhail and Rosen, H. and D{\"o}tsch, Horst}, title = {Sensitive magneto-optical sensors for visualization of magnetic fields using garnet films of specific orientations}, series = {Journal of Applied Physics}, volume = {92}, journal = {Journal of Applied Physics}, publisher = {AIP}, doi = {10.1063/1.1516839}, abstract = {Garnet films of high Faraday rotation are applied as magneto-optical sensors to visualize the spatial distribution of magnetic fields. Using specific orientations, the induced anisotropy can generate an easy plane of magnetization which is inclined with respect to the film plane. If the magnetization lies in this plane a very high sensitivity can be achieved. The dependence of the geometrical orientation of the easy plane on the growth direction is calculated and the sensitivity and dynamic range are derived. Experimental results of a [112] oriented garnet film are in good agreement with calculations.}, language = {en} } @inproceedings{DoetschHolthausTrifonovetal., author = {D{\"o}tsch, Horst and Holthaus, Carsten and Trifonov, A. and Klank, Michael and Hagedorn, Oliver and Shamonin (Chamonine), Mikhail and Sch{\"u}tzmann, J.}, title = {Application of Magnetic Garnet Films for Magnetooptical Imaging of Magnetic Field Distributions}, series = {MRS Online Proceedings Library}, booktitle = {MRS Online Proceedings Library}, publisher = {Springer}, doi = {10.1557/PROC-834-J6.1}, pages = {18 -- 29}, abstract = {Rare-earth iron garnet films of high quality can be grown by liquid phase epitaxy on paramagnetic substrates of gadolinium galliumgarnet. Such films are currently used for imaging of the spatial distribution of magnetic fields. This application is based on the Faraday rotation which can strongly be enhanced by bismuth incorporation. The physical properties of the films can be controlled by the chemical composition, the growth conditions and the crystallographic orientation. The sensor properties like sensitivity, dynamic range, signal linearity and unambiguity must be optimized according to the application desired. These properties, however, are not independent of each other. In addition, they strongly depend on the optical wavelength. Thus, it is necessary to find compromises. The influence of Faraday rotation, Faraday ellipticity, optical absorption, magnetic anisotropies and film thickness on the performance of a magnetooptical indicator film is investigated. Based on the swing of the photoresponse, a new optimization process is introduced. The process is experimentally verified and application examples are demonstrated. Furthermore, two methods are presented to enhance the sensitivity of magnetooptical sensors. Using specific crystallographic orientations, an easy plane of magnetization can be induced which is inclined with respect to the film plane. If the magnetization lies in this plane a very high sensitivity is achieved. The dependence of the geometrical orientation of the easy plane on the growth direction is calculated and the sensitivity and dynamic range are derived. Experimental results of a [112] oriented garnet film are in good agreement with calculations. Garnet films which are magnetized along the film normal due to a strong induced uniaxial anisotropy support magnetic domains. If the collapse field perpendicular to the film plane is small, such films can be used as very sensitive indicator films. Such films are easier to prepare than sensitive in-plane films. However, the spatial resolution is limited by the size of the domains. This disadvantage can be avoided by applying a bias field in the film plane. Directly at the in-plane collapse field the sensor film is in-plane magnetized yielding high spatial resolution at still high sensitivity. The variation of magnetooptical images with in-plane induction is demonstrated. Experimental results are in agreement with calculations.}, language = {en} }