@article{LukyanetsSnarskiiShamoninChamonineetal., author = {Lukyanets, S. and Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Bakaev, V. V.}, title = {Calculation of magnetic leakage field from a surface defect in a linear ferromagnetic material: an analytical approach}, series = {NDT \& E International}, volume = {36}, journal = {NDT \& E International}, number = {1}, publisher = {Elsevier}, doi = {10.1016/S0963-8695(02)00071-3}, pages = {51 -- 55}, abstract = {A novel analytical approach for calculating the magnetic leakage field from surface defects is proposed and demonstrated for the case of a linear ferromagnetic material. The novelty of the theory is that it relates the distribution of induced magnetic charges to the surface shape. An excellent agreement between the analytical and numerical results is shown. The functional relations between different magnetic field components are discussed.}, language = {en} } @article{BakaevSnarskiiShamoninChamonine, author = {Bakaev, V. V. and Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail}, title = {The permeability and remanent magnetization of a randomly inhomogeneous two-phase medium}, series = {Technical Physics}, volume = {47}, journal = {Technical Physics}, publisher = {Springer}, doi = {10.1134/1.1435901}, pages = {125 -- 128}, abstract = {A randomly inhomogeneous composite consisting of two, ferromagnetic and nonmagnetic (para-or diamagnetic), phases is considered. The dependence of the effective permeability of the composite on the concentration of the ferromagnetic phase and on the applied magnetic field is found for the case of the negligible hysteresis loop. When the hysteresis loop is appreciable, the remanent magnetization as a function of the ferromagnet concentration is calculated.}, language = {en} } @article{ShamoninChamonineShamoninaKalininetal., author = {Shamonin (Chamonine), Mikhail and Shamonina, Ekaterina and Kalinin, V. and Solymar, L.}, title = {Properties of a metamaterial element: Analytical solutions and numerical simulations for a singly split double ring}, series = {Journal of Applied Physics}, volume = {95}, journal = {Journal of Applied Physics}, number = {7}, publisher = {AIP}, doi = {10.1063/1.1652251}, abstract = {An equivalent circuit, consisting of bulk and distributed elements, is derived for describing the properties of a potential metamaterial element capable of providing negative effective permeability. It is the singly split double ring (SSDR), a special case of the split ring resonator (J. B. Pendry et al., IEEE Trans. Microwave Theory Tech. 47, 2075 (1999)), obtained when the gap capacitance in the inner ring is infinitely large. The variables are the inter-ring voltage and the currents flowing in the inner and outer rings. The excitation is assumed in the form of a spatially constant temporally varying magnetic field. The functions, showing the angular variation of the variables, are found by solving a set of differential equations with boundary conditions imposed at the position of the split. It is shown from the analytical solution that the SSDR can have resonant frequencies in the full spectrum from very low to very high frequencies. It is pointed out in particular that whenever the mean diameter of the ring is equal to an odd multiple of the half wavelength it is always possible to find a set of parameters which will give rise to resonance. As examples the resonant frequencies are determined for eight sets of parameters. Results are also derived by replacing the distributed circuit with a number of discrete circuits. It is finally shown that the results obtained from the equivalent circuit model are in excellent agreement with those derived from the MICRO-STRIPES numerical package which solves Maxwell's equations in the time domain.}, language = {en} } @article{SnarskiiShamoninChamonineZhenirovskyy, author = {Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Zhenirovskyy, M. I.}, title = {Effective properties of macroscopically non-uniform ferromagnetic composite materials}, series = {Zhurnal Eksperimental'noj i Teoreticheskoj Fiziki - Journal of Experimental and Theoretical Physics (JETP)}, volume = {123}, journal = {Zhurnal Eksperimental'noj i Teoreticheskoj Fiziki - Journal of Experimental and Theoretical Physics (JETP)}, number = {1}, publisher = {Akademija Nauk SSSR}, address = {Moscow}, pages = {79 -- 92}, language = {en} } @article{ApelsmeierSchmaussShamoninChamonine, author = {Apelsmeier, Andreas and Schmauss, Bernhard and Shamonin (Chamonine), Mikhail}, title = {Compensation of parasitic losses in an extrinsic fiber-optic temperature sensor based on intensity measurement}, series = {Sensors and Actuators A: Physical}, volume = {173}, journal = {Sensors and Actuators A: Physical}, number = {1}, doi = {10.1016/j.sna.2011.10.015}, pages = {49 -- 54}, abstract = {A method of referencing in an extrinsic optical fiber sensor system utilizing temperature dependence of the absorption edge in a semiconductor crystal (semi-insulating iron-doped indium phosphide) is demonstrated. The intensity reference is provided by controlling the temperature of an LED source and transmission measurements with different emission spectra. A transient operation regime is introduced. The entire process is controlled by a microprocessor unit. The performance of the sensor system is investigated and it is shown that the connector losses may be compensated for. Contrary to the published works performed with GaAs crystals it was not observed that the absorption coefficient of the semiconductor follows the law for idealized direct-gap semiconductor but can be described by the so-called Urbach tail. Since the proposed sensor system comprises a single LED source, simple electronics and no optical fiber couplers it is promising for realization of low-cost fiber-optic temperature sensors, e.g. for power transformer monitoring or magnetic resonance imaging applications.}, language = {en} } @article{TrautnerSchmaussShamoninChamonine, author = {Trautner, Ralph and Schmauss, Bernhard and Shamonin (Chamonine), Mikhail}, title = {Herstellung und Charakterisierung eines extrinsischen faseroptischen Elementarsensors zur Temperaturmessung}, series = {tm - Technisches Messen}, volume = {75}, journal = {tm - Technisches Messen}, number = {10}, publisher = {De Gruyter}, doi = {10.1524/teme.2008.0866}, abstract = {Es werden Herstellung und Charakterisierung eines faseroptischen Elementarsensors zur Temperaturmessung vorgestellt. Der Sensorkopf in Form eines Prismas aus Indiumphosphid nutzt die Temperaturabh{\"a}ngigkeit der Absorptionskante des Halbleitermaterials. Aufgrund der Abmessungen des Prismas im Grenzbereich von Feinmechanik zu Mikrosystemtechnik ist ein angepasstes Herstellungsverfahren notwendig.}, language = {de} } @article{SydorukRadkovskayaZhuromskyyetal., author = {Sydoruk, O. and Radkovskaya, Anna A. and Zhuromskyy, Oleksandr and Shamonina, Ekaterina and Shamonin (Chamonine), Mikhail and Stevens, Chris J. and Faulkner, Grahame and Edwards, David J. and Solymar, L.}, title = {Tailoring the near-field guiding properties of magnetic metamaterials with two resonant elements per unit cell}, series = {PHYSICAL REVIEW B}, volume = {73}, journal = {PHYSICAL REVIEW B}, number = {22}, publisher = {APS}, doi = {10.1103/PhysRevB.73.224406}, abstract = {A theoretical and experimental study of magnetic metamaterials with unit cells containing two resonant elements is presented. The properties of these structures, consisting of split rings, are governed by strongly anisotropic magnetic coupling between individual elements. This coupling leads to propagation of slow magnetoinductive waves in the vicinity of the resonant frequency. The wavelength of magnetoinductive waves is much smaller than the free-space wavelength of the electromagnetic radiation. This opens up the possibility of manipulating the near field on a subwavelength scale. We develop a theoretical formulation for coupled chains of metamaterial elements allowing the tailoring of their guiding properties in the near field. In a comprehensive analysis modes of coupled waveguides supporting forward and/or backward waves are identified and the corresponding hybridization mechanisms for dispersion equations of magnetoinductive waves are determined. Analytical predictions are verified both experimentally and numerically on a variety of coupled waveguides. The approach can be employed for the design of near-field manipulating devices.}, language = {en} } @article{HesmerTatartschukZhuromskyyetal., author = {Hesmer, Frank and Tatartschuk, Eugen and Zhuromskyy, Oleksandr and Radkovskaya, Anna A. and Shamonin (Chamonine), Mikhail and Hao, Tong and Stevens, Chris J. and Faulkner, Grahame and Edwards, David J. and Shamonina, Ekaterina}, title = {Coupling mechanisms for split ring resonators: Theory and experiment}, series = {Physica status solidi b}, volume = {244}, journal = {Physica status solidi b}, number = {4}, publisher = {Wiley}, doi = {10.1002/pssb.200674501}, pages = {1170 -- 1175}, abstract = {We study experimentally and theoretically coupling mechanisms between metamaterial elements of the split ring resonator (SRR) type. We show that, depending on the orientation of the elements relative to each other, the coupling may be either of magnetic or electric type or a combination of both. Experimental results on SRRs with resonances around 1.7-1.9 GHz agree quantitatively with results of simulations (CST Microwave Studio). Further simulations provide analysis for a variety of SRRs both in the GHz and in the 20 THz frequency regions. The variety of coupling mechanisms can be employed in designing near field manipulating devices based on propagation of slow waves.}, 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{LukyanetsSnarskiiShamoninChamonineetal., author = {Lukyanets, S. and Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Bakaev, V. V.}, title = {Calculation of magnetic leakage field from a surface defect in a linear ferromagnetic material: an analytical approach}, series = {NDT \& E International}, volume = {36}, journal = {NDT \& E International}, number = {1}, publisher = {Elsevier}, doi = {10.1016/s0963-8695(02)00071-3}, pages = {51 -- 55}, abstract = {A novel analytical approach for calculating the magnetic leakage field from surface defects is proposed and demonstrated for the case of a linear ferromagnetic material. The novelty of the theory is that it relates the distribution of induced magnetic charges to the surface shape. An excellent agreement between the analytical and numerical results is shown. The functional relations between different magnetic field components are discussed.}, language = {en} } @article{BakaevSnarskiiShamoninChamonine, author = {Bakaev, V. V. and Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail}, title = {The permeability and remanent magnetization of a randomly inhomogeneous two-phase medium}, series = {Technical Physics}, volume = {47}, journal = {Technical Physics}, number = {1}, publisher = {Springer}, doi = {10.1134/1.1435901}, pages = {125 -- 128}, abstract = {A randomly inhomogeneous composite consisting of two, ferromagnetic and nonmagnetic (para-or diamagnetic), phases is considered. The dependence of the effective permeability of the composite on the concentration of the ferromagnetic phase and on the applied magnetic field is found for the case of the negligible hysteresis loop. When the hysteresis loop is appreciable, the remanent magnetization as a function of the ferromagnet concentration is calculated.}, language = {en} } @article{BakaevSnarskiiShamoninChamonine, author = {Bakaev, V. V. and Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail}, title = {The effective magnetic permeability of a two-phase fibred ferromagnetic composite}, series = {Technical Physics}, volume = {46}, journal = {Technical Physics}, number = {12}, publisher = {Springer}, doi = {10.1134/1.1427995}, pages = {1571 -- 1574}, language = {en} } @article{KovalevBelyaevavonHofenetal., author = {Kovalev, Alexander and Belyaeva, Inna A. and von Hofen, Christian and Gorb, Stanislav and Shamonin (Chamonine), Mikhail}, title = {Magnetically Switchable Adhesion and Friction of Soft Magnetoactive Elastomers}, series = {Advanced Engineering Materials}, volume = {24}, journal = {Advanced Engineering Materials}, number = {10}, publisher = {WILEY-VCH}, doi = {10.1002/adem.202200372}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-45283}, pages = {1 -- 8}, abstract = {Herein, the effect of an applied moderate (~240 mT) magnetic field on the work of adhesion (WoA) of mechanically soft (the shear modulus ~10 kPa) magnetoactive elastomer (MAE) samples with two different mass fractions (70 and 80 wt\%) of carbonyl iron powder (CIP) is concerned. The unfilled elastomer sample is used for comparison. Due to some sedimentation of filling particles, the concentration of inclusions in thin (~10 μm) subsurface layers is different. It is shown that the WoA increases (up to 1.8-fold) on the particle-enriched side (PES) in the magnetic field and its value is higher for higher filler concentration. On the particle-depleted side (PDS), WoA does not depend on particle concentration and on the magnetic field. Adhesion and friction are coupled in MAEs. No statistically significant difference in the friction coefficient, determined from the extended Amontons´ law, depending on sample side, CIP concentration, or presence of magnetic field is found. However, the PDS in the magnetic field demonstrates significantly higher critical shear stress compared to that for the PES or PDS in the absence of magnetic field. Correlations between different surface properties are discussed. Obtained results are useful for the development of magnetically controllable soft robots.}, language = {en} } @article{LohmeyerShamoninChamonineHertel, author = {Lohmeyer, Manfred and Shamonin (Chamonine), Mikhail and Hertel, Peter}, title = {Integrated optical circulator based on radiatively coupled magneto-optic waveguides}, series = {Optical Engineering}, volume = {36}, journal = {Optical Engineering}, number = {3}, publisher = {SPIE}, doi = {10.1117/1.601255}, pages = {889 -- 895}, abstract = {In a three-guide coupler with multimode central waveguide, more than two modes of the entire structure participate in the coupling between the outer waveguides. Using a three-mode approximation we found simple conditions for complete power transfer between the outer waveguides: the device length has to match certain multiples of the con- ventionally defined coupling length. The specific form of the relevant modes allows us to design a magneto-optic isolator or circulator with significantly reduced device length (as compared to the conventional nonreciprocal coupler). The performance of the proposed devices is simulated by propagating-mode calculations. Estimates for admissible fabrication tolerances for the layer thicknesses are presented.}, language = {en} } @article{BelyaevaKramarenkoStepanovetal., author = {Belyaeva, Inna A. and Kramarenko, Elena Yu and Stepanov, Gennady V. and Sorokin, Vladislav V. and Stadler, Dominik and Shamonin (Chamonine), Mikhail}, title = {Transient magnetorheological response of magnetoactive elastomers to step and pyramid excitations}, series = {SOFT MATTER}, volume = {12}, journal = {SOFT MATTER}, number = {11}, publisher = {ROYAL SOC CHEMISTRY}, doi = {10.1039/c5sm02690c}, pages = {2901 -- 2913}, abstract = {Transient rheological response of magnetoactive elastomers is experimentally studied using dynamic torsion at a fixed oscillation frequency in temporally stepwise changing magnetic fields and oscillation amplitudes. For step magnetic-field excitations, at least three exponential functions are required to reasonably describe the time behavior of the storage shear modulus over long time scales (>10(3) s). The deduced characteristic time constants of the corresponding rearrangement processes of the filler network differ approximately by one order of magnitude: tau(1) less than or similar to 10(1) s, tau(2) similar to 10(2) s, and tau(3) similar to 10(3) s. The sudden imposition of the external magnetic field activates a very fast rearrangement process with the characteristic time under 10 s, which cannot be determined more precisely due to the measurement conditions. Even more peculiar transient behavior has been observed during pyramid excitations, when either the external magnetic field was first stepwise increased and then decreased in a staircase manner at a fixed strain amplitude gamma or the strain amplitude gamma was first stepwise increased and then decreased in a staircase manner at a fixed magnetic field. In particular, the so-called "cross-over effect'' has been identified in both dynamical loading programs. This cross-over effect seems to be promoted by the application of the external magnetic field. The experimental results are discussed in the context of the specific rearrangement of the magnetic filler network under the simultaneous action of the external magnetic field and shear deformation. Striking similarities of the observed phenomena to the structural relaxation processes in glassy materials and to the jamming transition of granular materials are pointed out. The obtained results are important for fundamental understanding of material behavior in magnetic fields as well as for the development of devices on the basis of magnetoactive elastomeric materials.}, language = {en} } @article{BelyaevaKramarenkoShamoninChamonine, author = {Belyaeva, Inna A. and Kramarenko, Elena Yu and Shamonin (Chamonine), Mikhail}, title = {Magnetodielectric effect in magnetoactive elastomers: Transient response and hysteresis}, series = {POLYMER}, volume = {127}, journal = {POLYMER}, publisher = {ELSEVIER}, doi = {10.1016/j.polymer.2017.08.056}, pages = {119 -- 128}, abstract = {Magnetodielectric properties of magnetoactive elastomers comprising micrometer-sized iron particles dispersed in compliant elastomer matrices are experimentally studied in stepwise time-varying dc magnetic fields. It is found that imposition of magnetic field significantly increases both the effective lossless permittivity of these composite materials as well as their effective conductivity. These magnetodielectric effects are more pronounced for larger concentrations of soft-magnetic filler particles and softer elastomer matrices. The largest observed relative change of the effective dielectric constant in the maximum magnetic field of 0.57 T is of the order of 1000\%. The largest observed absolute change of the loss tangent is approximately 0.8. The transient response of the magnetodielectric effect to a step magnetic-field excitation can be rather complex. It changes from a simple monotonic growth with time for small magnetic-field steps (<0.1 T) to a non-monotonic behavior with a significant rapidly appearing overshoot for large magnetic-field steps (>0.3 T). The settling time to the magnetic-field step excitation can reach roughly 1000 s and it depends on the applied magnetic field and sample composition. There is also significant hysteresis of the magnetodielectric effect on the externally applied magnetic field. These findings are attributed to the rearrangement of ferromagnetic filler particles in external magnetic fields. The results will be useful for understanding and predicting the transient behavior of magnetoactive elastomers in applications where the control magnetic field is time dependent. (C) 2017 Elsevier Ltd. All rights reserved.}, language = {en} } @article{SorokinBelyaevaShamoninChamonineetal., author = {Sorokin, Vladislav V. and Belyaeva, Inna A. and Shamonin (Chamonine), Mikhail and Kramarenko, Elena Yu}, title = {Magnetorheological response of highly filled magnetoactive elastomers from perspective of mechanical energy density: Fractal aggregates above the nanometer scale?}, series = {Physical Review E}, volume = {95}, journal = {Physical Review E}, number = {6}, publisher = {Amer Physical Soc}, doi = {10.1103/PhysRevE.95.062501}, abstract = {The dynamic shear modulus of magnetoactive elastomers containing 70 and 80 mass \% of carbonyl iron microparticles is measured as a function of strain amplitude via dynamic torsion oscillations in various magnetic fields. The results are presented in terms of the mechanical energy density and considered in the framework of the conventional Kraus model. The form exponent of the Kraus model is further related to a physical model of Huber et al. [Huber et al., J. Phys.: Condens. Matter 8, 409 (1996)] that uses a realistic representation for the cluster network possessing fractal structure. Two mechanical loading regimes are identified. At small strain amplitudes the exponent beta of the Kraus model changes in an externally applied magnetic field due to rearrangement of ferromagnetic-filler particles, while at large strain amplitudes, the exponent beta seems to be independent of the magnetic field. The critical mechanical energy characterizing the transition between these two regimes grows with the increasing magnetic field. Similarities between agglomeration and deagglomeration of magnetic filler under simultaneously applied magnetic field and mechanical shear and the concept of jamming transition are discussed. It is proposed that the magnetic field should be considered as an additional parameter to the jamming phase diagram of rubbers filled with magnetic particles.}, language = {en} } @article{BelyaevaKleppLemmeletal., author = {Belyaeva, Inna A. and Klepp, J{\"u}rgen and Lemmel, Hartmut and Shamonin (Chamonine), Mikhail}, title = {Feasibility of Probing the Filler Restructuring in Magnetoactive Elastomers by Ultra-Small-Angle Neutron Scattering}, series = {Applied Sciences}, volume = {11}, journal = {Applied Sciences}, number = {10}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/app11104470}, pages = {1 -- 9}, abstract = {Ultra-small-angle neutron scattering (USANS) experiments are reported on isotropic magnetoactive elastomer (MAE) samples with different concentrations of micrometer-sized iron particles in the presence of an in-plane magnetic field up to 350 mT. The effect of the magnetic field on the scattering curves is observed in the scattering vector range between 2.5 x 10(-5) and 1.85 x 10(-4) angstrom(-1). It is found that the neutron scattering depends on the magnetization history (hysteresis). The relation of the observed changes to the magnetic-field-induced restructuring of the filler particles is discussed. The perspectives of employing USANS for investigations of the internal microstructure and its changes in magnetic field are considered.}, language = {en} } @article{GlavanBelyaevaShamoninChamonine, author = {Glavan, Gašper and Belyaeva, Inna A. and Shamonin (Chamonine), Mikhail}, title = {On the Piezomagnetism of Magnetoactive Elastomeric Cylinders in Uniform Magnetic Fields: Height Modulation in the Vicinity of an Operating Point by Time-Harmonic Fields}, series = {Polymers}, volume = {16}, journal = {Polymers}, number = {19}, doi = {10.3390/polym16192706}, abstract = {Soft magnetoactive elastomers (MAEs) are currently considered to be promising materials for actuators in soft robotics. Magnetically controlled actuators often operate in the vicinity of a bias point. Their dynamic properties can be characterized by the piezomagnetic strain coefficient, which is a ratio of the time-harmonic strain amplitude to the corresponding magnetic field strength. Herein, the dynamic strain response of a family of MAE cylinders to the time-harmonic (frequency of 0.1-2.5 Hz) magnetic fields of varying amplitude (12.5 kA/m-62.5 kA/m), superimposed on different bias magnetic fields (25-127 kA/m), is systematically investigated for the first time. Strain measurements are based on optical imaging with sub-pixel resolution. It is found that the dynamic strain response of MAEs is considerably different from that in conventional magnetostrictive polymer composites (MPCs), and it cannot be described by the effective piezomagnetic constant from the quasi-static measurements. The obtained maximum values of the piezomagnetic strain coefficient (∼102 nm/A) are one to two orders of magnitude higher than in conventional MPCs, but there is a significant phase lag (35-60°) in the magnetostrictive response with respect to an alternating magnetic field. The experimental dependencies of the characteristics of the alternating strain on the amplitude of the alternating field, bias field, oscillation frequency, and aspect ratio of cylinders are given for several representative examples. It is hypothesized that the main cause of observed peculiarities is the non-linear viscoelasticity of these composite materials.}, language = {en} } @article{JezeršekKrieglKravanjaetal., author = {Jezeršek, Matija and Kriegl, Raphael and Kravanja, Gaia and Hribar, Luka and Drevenšek-Olenik, Irena and Unold, Heiko and Shamonin (Chamonine), Mikhail}, title = {Control of Droplet Impact through Magnetic Actuation of Surface Microstructures}, series = {Advanced Materials Interfaces}, volume = {10}, journal = {Advanced Materials Interfaces}, number = {11}, publisher = {Wiley}, doi = {10.1002/admi.202202471}, abstract = {An effective method for on-demand control over the impact dynamics of droplets on a magnetoresponsive surface is reported. The surface is comprised of micrometer-sized lamellas from a magnetoactive elastomer on a copper substrate. The surface itself is fabricated using laser micromachining. The orientation of the lamellae is switched from edge-on (orthogonal to the surface) to face-on (parallel to the surface) by changing the direction of a moderate (<250 mT) magnetic field. This simple actuation technique can significantly change the critical velocities of droplet rebound, deposition, and splashing. Rebound and deposition regimes can be switched up to Weber number We < 13 ± 3, while deposition and splashing can be switched in the range of 32 < We < 52. Because a permanent magnet is used, no permanent power supply is required for maintaining the particular regime of droplet impact. The presented technology is highly flexible and enables selective fabrication and actuation of microstructures on complex devices. It has great potential for applications in soft robotics, microfluidics, and advanced thermal management.}, language = {en} } @article{GlavanKettlBrunhuberetal., author = {Glavan, Gašper and Kettl, Wolfgang and Brunhuber, Alexander and Shamonin (Chamonine), Mikhail and Drevenšek-Olenik, Irena}, title = {Effect of Material Composition on Tunable Surface Roughness of Magnetoactive Elastomers}, series = {Polymers}, volume = {11}, journal = {Polymers}, number = {4}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/polym11040594}, pages = {1 -- 13}, abstract = {We investigated magnetic-field-induced modifications of the surface roughness of magnetoactive elastomers (MAEs) with four material compositions incorporating two concentrations of ferromagnetic microparticles (70 wt\% and 80 wt\%) and exhibiting two shear storage moduli of the resulting composite material (about 10 kPa and 30 kPa). The analysis was primarily based on spread optical reflection measurements. The surfaces of all four materials were found to be very smooth in the absence of magnetic field (RMS roughness below 50 nm). A maximal field-induced roughness modification (approximately 1 m/T) was observed for the softer material with the lower filler concentration, and a minimal modification (less than 50 nm/T) was observed for the harder material with the higher filler concentration. All four materials showed a significant decrease in the total optical reflectivity with an increasing magnetic field as well. This effect is attributed to the existence of a distinct surface layer that is depleted of microparticles in the absence of a magnetic field but becomes filled with particles in the presence of the field. We analyzed the temporal response of the reflective properties to the switching on and off of the magnetic field and found switching-on response times of around 0.1 s and switching-off response times in the range of 0.3-0.6 s. These observations provide new insight into the magnetic-field-induced surface restructuring of MAEs and may be useful for the development of magnetically reconfigurable elastomeric optical surfaces.}, language = {en} }