A5012525291- Physics of Superconductivity and Magnetism
- Shape Memory Alloy Transformations
- Magnetic and transport properties of perovskites and related materials
- Magnetic Properties and Applications
- Advanced Condensed Matter Physics
- Heusler alloys: electronic and magnetic properties
- Magnetic Properties of Alloys
- Superconducting Materials and Applications
- Magnetic properties of thin films
- Superconductivity in MgB2 and Alloys
- Transition Metal Oxide Nanomaterials
- Magnetic confinement fusion research
- Copper-based nanomaterials and applications
- Intermetallics and Advanced Alloy Properties
- MXene and MAX Phase Materials
- ZnO doping and properties
- Iron-based superconductors research
- Particle accelerators and beam dynamics
- Theoretical and Computational Physics
- Piezoelectric Actuators and Control
- Rare-earth and actinide compounds
- 2D Materials and Applications
- Nuclear and radioactivity studies
- Geomagnetism and Paleomagnetism Studies
- Scientific Research and Discoveries
Czech Academy of Sciences, Institute of Physics
2015-2024
Czech Academy of Sciences
2012-2024
Czech Academy of Sciences, Institute of Plasma Physics
2008-2015
Epitaxially grown full Heusler alloy of Rh2MnSb thin films were prepared for the first time using DC magnetron sputtering. The deposited on MgO [001] substrates with a deposition temperature 600{\deg}C, 700{\deg}C, and 800{\deg}C. We report structural, morphological, optical, magneto-optical, magnetic properties 200 nm nominal thickness. grown-at-600{\deg}C film was close to stoichiometric exhibited L21 ordering typical alloys. single-phase had tetragonal structure lattice parameters bulk...
Low twinning stress (TS) is a prerequisite for magnetic shape memory functionality in ferromagnetic martensites. We compare Ni 50 Mn 28 Ga 22 (nominal at.%) single crystals from four different producers to reveal the effect of crystal quality on TS. Near reverse martensite transformation, TS generally low, about 1 MPa, regardless mosaicity up 1.7° and chemical composition deviations 2 at.% Mn. Pure type I II twin boundaries occur with smooth gradients. The corresponding temperature...
The combination of enlarged magnetic coercivity and shape memory (MSM) functionality is essential for novel magnetomechanical effects in MSM alloys. We found that increasing the density thermal antiphase boundaries (APBs) provides a method to increase without deteriorating functionality. APB was controlled by different heat treatments Ni–Mn–Ga (–B) single crystals with five-layered modulated martensite structure. Slow cooling ∼1 K/min through B2′–L21 transition resulted low (<1/micrometer)...
Systematic doping by transition elements Fe, Co and Ni on each site of Ni2MnGa alloy reveal that in bulk material the increase martensitic transformation temperature is usually accompanied decrease ferromagnetic Curie temperature, vice versa. The highest (571 K) was found for Ni50.0Mn25.4(Ga20.3Ni4.3) with result a reduction 55 K. point (444 (Ni44.9Co5.1)Mn25.1Ga24.9; however, reduced to 77 dependence better scaled Ne/a parameter (number non-bonding electrons per atom) compared usual e/a...
Full Heusler Co2TiSn thin film were grown by DC magnetron sputtering on MgO(001) substrates at temperatures from ambient up to 800°C. The epitaxial films with full structure and high purity achieved 700°C thickness ranging ~ 20 nm over 1000 enabling deeper study of the growth effect properties. state was investigated wide range techniques including atomic force electron microscopy, X-ray diffraction photoelectron spectroscopy, magnetometry, magnetooptical ellipsometry supported ab initio...
Magnetic induction and current transport techniques were employed to test the electromagnetic performance of 22 samples superconducting REBaCuO tapes several manufacturers with aim select best candidates for wiring new generation magnets fusion reactors. An extraordinary shape pinning force density as a function magnetic field was observed in 'advanced pinning, AP' SuperPower tapes. The induced currents enabled us classify show ones, at low temperatures high fields on one hand other hand....
Magnetic properties of Ni46Mn24Ga22Co4Cu4, (Ni45Mn23Ga22Co5Cu5, Ni46Mn22.5Ga23Co5Cu3.5) tetragonal martensites with c/a ≈ 1.14 exhibiting near 10% magnetic field-induced strain (MFIS) were investigated between 10 and 500 K up to 9 T field. The (001) easy plane magnetocrystalline anisotropy K1(300 K)= − 1.95 ∙ 105 J m− 3 (K2 < 6%|K1|, K3 2%|K1|, MS(300 K) = 63 Am2/kg) was about 30% lower than in the non-doped Ni50.5Mn30.4Ga19.1 reference, which can be related a reduced ratio doped material....
The model of thermally activated relaxation developed and successfully tested on high-Tc superconductors (Jirsa et al 2004 Phys. Rev. B 70 0245251) was applied to magnetic data a bulk spark-plasma sintered MgB2 sample elucidate its behavior. the related borides form superconductor class lying between classical superconductors. In accord with this classification, phenomena were found be about ten times weaker than in cuprates. Vortex pinning analyzed terms field dependence force density...
Batch melt-growth processing of YBa2Cu3Oy levitation disks cold seeded by Sm-123 single crystals doped MgO is described. The process capable a simultaneous fabrication up to 64 pieces has been developed and successfully tested as necessary step towards planned production capacity several thousand year. Diameters the varied from 14 mm 56 mm. Main attention was paid 28 in diameter. This dimension occurs be best compromise various points view: material homogeneity, pellet quality, loss, time...
Abstract In bulk high-temperature superconductors, Ag is usually used as an additive thus improving mechanical performance. MgB 2 doped with Ag, the reacts Mg, forming Mg–Ag phases acting a vortex pinning medium. this work, we analyze electromagnetic and properties of 1 wt% 4, 4 Dy O 3 , prepared at Shibaura Institute Technology (SIT), Tokyo. three compounds Mg x B + = 1, 1.075, 1.1, effect excess was studied. The magnetic moment measured by vibrating sample magnetometer (VSM). Pinning...
Ferromagnetic shape-memory CoNiGa alloys have attracted much scientific interest due to their potential alternative use as high-temperature alloys, bearing a high prospect for actuation and damping applications at elevated temperatures. Yet, polycrystalline CoNiGa, strong orientation dependence of transformation strains, suffers from intergranular fracture. Here, two multi-grain samples were prepared by novel hot extrusion process that can promote favourable grain-boundary distribution...
Electromagnetic performance of superconducting REBaCuO tapes from several manufacturers was investigated in response to neutron irradiation. The aim test the feasibility using these for wiring high-T c magnets fusion reactors. Magnetic induction employed determine critical currents. In non-irradiated SuNAM, SuperOx, and SuperPower without additional pinning centers, normalized force density as a function magnetic field, h, exhibited commonly observed single peak at about h = 0.2 whole...
The key for the existence of magnetic induced reorientation is strong magnetocrystalline anisotropy, i.e., coupling between ferroelastic and ferromagnetic ordering. To increase transformation temperatures thus functionality, various elemental alloying in Ni-Mn-Ga tried. We analyzed more than twenty polycrystalline alloys alloyed by small amount (up to 5atom%) transitional metals Co, Fe, Ni, Cu value anisotropy search general trends with alloying. In agreement previous reports, we found that...
Fe75−xMn25Gax Heusler-like compounds were investigated in a wide range of Fe/Ga ratios while keeping the Mn content constant and equal 25 at% order to elucidate interplay between magnetic properties composition. Materials prepared by arc-melting from pure elements subsequently annealed. Experimental investigations focused on magnetization behavior temperature 4 1000 K field up 9 T. Optical magneto-optical (MO) measurements employed shed more light state electronic structure materials....