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Effect of ion beam irradiation and annealing on magnetic properties of FeRh nanostructures
Zadorozhnii, Oleksii ; Turčan, Igor (referee) ; Staňo, Michal (advisor)
Fazový přechod prvního řádu z antiferomagnetického do feromagnetického stavu v Fe50Rh50 z něj činí vhodný materiál pro nové generace spinových elektronických zařízení s nízkou spotřebou. Tato práce se zabývá způsoby, jak lze teplotu fázového přechodu železo-rhodia (FeRh) lokálně ovlivnit pomocí fokusovaneho iontového svazku (FIB) a žíhání. FIB byl zvolen vzhledem k tomu, že slitina FeRh vykazuje magnetickou citlivost na stupeň jejího chemického uspořádání, což je charakteristické pro všechny slitiny feromagnetických a neferomagnetických kovů. Tepelné žíhaní umožňuje obnovení krystalografického uspořádání, a uvolnění mřižkových defektů a dislokací. Magnetické vzory byly vyrobeny za použití FIB na bázi galia a žíhány ve vakuu. Topografie a magnetické chování těchto iontově ozářených vzorů byly zkoumány pomocí mikroskopie atomárních a magnetických sil při různých teplotách, a ukázaly jasnou závislost mezi dávkou iontového záření a magnetickou odezvou ve stavu před a po žíhání.
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Application onf the Focused Ion on Electron Beam in Nanotechnologies
Šamořil, Tomáš ; Mikulík, Petr (referee) ; Jiruše, Jaroslav (referee) ; Šikola, Tomáš (advisor)
Nowadays, the systems that allow simultaneous employment of both focused electron and ion beams are very important tools in the field of micro- and nanotechnology. In addition to imaging and analysis, they can be used for lithography, which is applied for preparation of structures with required shapes and dimensions at the micrometer and nanometer scale. The first part of the thesis deals with one lithographic method – focused electron or ion beam induced deposition, for which a suitable adjustment of exposition parameters is searched and quality of deposited metal structures in terms of shape and elemental composition studied. Subsequently, attention is paid also to other types of lithographic methods (electron or ion beam lithography), which are applied in preparation of etching masks for the subsequent selective wet etching of silicon single crystals. In addition to optimization of mentioned techniques, the application of etched silicon surfaces for, e.g., selective growth of metal structures has been studied. The last part of the thesis is focused on functional properties of selected 2D or 3D structures.
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Interaction of a SNOM tip with electromagnetic near-field produced by interference of surface plasmon polaritons
Jakub, Zdeněk ; Břínek, Lukáš (referee) ; Dvořák, Petr (advisor)
The aim of this bachelor’s thesis is fabrication of probes for scanning near-field optical microscope (SNOM) and testing of their functionality by measuring interference patterns of surface plasmon polaritons (SPP). The theoretical part deals with the basic properties of SPP’s and methods of their excitation and detection. In the experimental part, methods of sharp tip fabrication by chemical etching, thin film deposition by ion beam sputtering (IBS) or by ion beam assisted deposition (IBAD) and aperture opening by focused ion beam (FIB) are explained and demonstrated. Finally, interference patterns of SPP’s are measured with fabricated probes and the results are compared with the results obtained with commercially available probes.
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Advanced techniques of micro- and nanosystems fabrication for sensors
Márik, Marian ; Pekárek, Jan (referee) ; Hubálek, Jaromír (advisor)
The use of micro- and nanotechnologies is necessary in the development of advanced sensor systems. In this thesis few selected technologies were studied and tested on fabrication of creating two different systems for bioelectrical and electrochemical applications. For biolelectrical applications a chip with a pair of gold nanoelectrodes was designed and implemented. For electrochemical analysis a novel two electrode system was designed and realized, which should contribute by greater sensitivity and accuracy in amperometric detection compared with three-electrode systems in voltammetric analysis. The fabricated systems were tested and the results were discussed.
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Magnetic properties of materials based on metastable Fe-Ni thin films
Křižáková, Viola ; Uhlíř, Vojtěch (referee) ; Flajšman, Lukáš (advisor)
Metastable Fe78Ni22 thin films grown on Cu(100) substrates are known for their capability of structural and magnetic phase transition upon ion beam irradiation. This thesis focuses on characterization of magnetic properties of FeNi layers with the emphasis on their anisotropic behaviour. An analytical model describing magnetic anisotropies, in planar structures and thin films, and its modification for Fe78Ni22/Cu(100) system is described in the theoretical part. In the experimental part, the anisotropy of ion-beam-transformed FeNi structures is thoroughly studied. The transformed films and patterns exhibit four-fold magnetic anisotropy originating from bcc iron crystal structure. Further, the possibility of modification of the magnetic anisotropy type by selecting a proper focused ion beam scanning strategy during the transformation is demonstrated. In the last part of the thesis, the maximum achievable lateral resolution of focused ion beam transformed structures is explored and a prototypical magnonic crystal is prepared.
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Study of Properties of Surface Plasmon Polaritons on Magnetic Materials
Dvořák, Petr ; Schmidt, Eduard (referee) ; Kalousek, Radek (advisor)
The diploma thesis deals with the experimental study of surface plasmon polaritons (SPPs) on nano-structures with the Au/Co/Au multilayer. Plasmonic structures were prepared by the electron beam lithography and by the focused ion beam. A Scanning optical near-field microscope was used for detection of surface plasmon polaritons. SPPs were confirmed by the experiment with different polarizations of the illuminating light. Furthermore, differences in plasmon interference wavelengths was measured for different surface dielectric functions. Finally, the decantation of the SPPs interference image was measured in dependence on the external magnetic field.
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Magnetic transformation of metastable fcc Fe/Cu(100) films by focused ion beam
Gloss, Jonáš ; Cháb, Vladimír (referee) ; Urbánek, Michal (advisor)
Metastable paramagnetic face-centered cubic (fcc) Fe thin films deposited on a Cu(100) single-crystal are good candidates for focused ion-beam magnetic patterning, due to their structural and magnetic phase transformation to ferromagnetic body-centered cubic (bcc) Fe upon ion-beam irradiation. However, pure fcc Fe films undergo spontaneous transformation when their thickness exceeds 10 ML. This limit can be extended to approximately 22 ML by deposition of Fe at increased CO background pressures. We show that much thicker films can be grown by alloying with Ni, that stabilizes the fcc phase. The amount of Ni necessary to stabilize non-magnetic, metastable fcc Fe films in dependence on the residual background pressure during the deposition is determined and a phase diagram revealing the metastable region is presented. It is also shown that the stabilizing effect of CO can be removed by artificial O saturation of the surface and thus the Ni-stabilized films can be grown also in systems with lower vacuum. Finally, we present fabrication of micro- and nanostructures in 44 ML thick films of Fe alloyed with Ni on Cu(100) by focused ion beam.
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Growth of metastable fcc Fe thin films on Cu/Si(100) substrates
Horký, Michal ; Cháb, Vladimír (referee) ; Urbánek, Michal (advisor)
This diploma thesis deals with the preparation of epitaxially grown metastable paramagnetic Fe films alloyed by Ni on Cu/Si(100) substrates at RT. Molecular beam epitaxy of Cu(100) buffer layer was performed on H-Si(100) native SiO2 free samples treated by etching in HF or thermal treatment. The epitaxially grown Cu layers with thickness ranging from 50 up to 130 nm serves as suitable substrate for the deposition of 44-ML-thick paramagnetic Fe78Ni22. The film growth was taking place in CO atmosphere and as well as Ni it led to paramagnetic film stabilization. The structural and magnetic ion-beam-induced transformation of desired Fe-Ni structure was performed and propeties of irradiated films were characterized afterwards by MOKE. Then some specific patterns on Si(100) by e-beam litography were fabricated and they served as suitable matrix for Cu(100) buffer layer and paramagnetic Fe. Prepared Si(100), globally and locally deposited metal films were examined by LEED, XPS, AFM, AES, SEM a STM. The recorded results showed the possibility of paramagnetic films preparation on H-Si(100) where it was possible to make ferromagnetic patterns on paramagnetic background by irradiation of specific ion dose.
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Testing of the new UHV scanning electron microscope and design of its effusion cel
Šárközi, Rudolf ; Mach, Jindřich (referee) ; Bábor, Petr (advisor)
This work focus on the development and the design of the effusion cell that is able to deposit different materials in downward orientation. The Cell itself should be placed into the ultra-vacuum microscope (UHV-SEM) developed in TESCAN company in the collaboration with Institute of Physical Engineering. Theoretical part is devoted to the description of the electron microscope and its, in the future installed, parts, which will be used for the preparation and the analysis of the nanostructures. In this work, the first measurements with the electron microscope are presented, and the influence of mechanical vibrations to image quality is discussed.
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Electrotransport properties of the nanostructures fabricated by the FIB
Ostřížek, Petr ; Kolíbalová, Eva (referee) ; Urbánek, Michal (advisor)
The aim of this work is fabrication of nanostructures and measurement of their electrotransport properties. There are two different methods used for fabrication - electron beam lithography with sputtering of thin films and focused ion beam with deposition from gas phase. I-V characteristic was measured for characterisation of as prepared nanostructures - wires. Material of wires prepared by using of electron beam lithography was permalloy - an alloy of iron and nickel. Second types of wires prepared by using of chemical vapor deposition induced by focused ion beam was platinum based.
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