Gästföreläsare Klas Gunnarsson, tel , rum

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1 Funktionella material I, 2011 (preliminär, förväntade schemaändringar) Kurslitteratur Introduction to Magnetic Materials, B. D. Cullity, C. D. Graham, 2 nd edition, John Wiley& Sons Nätanteckningar Lärare Peter Svedlindh, tel , rum peter.svedlindh@angstrom.uu.se Gästföreläsare Klas Gunnarsson, tel , rum klas.gunnarsson@angstrom.uu.se Kursuppläggning Föreläsningar och räkneövningar ( 15 2 timmar) Laboration; Hårdmagnetiska material Projektarbete; Magnetooptisk Kerr effekt Elektromagnetiska förluster i mjukmagnetiska material Magnetiska kolloider magnetiseringsdynamik Permanentmagneter utan sällsynta jordartsmetaller Magnetism och generatorer Projektarbetet motsvarar i omfattning 2-3 dagars arbete och innefattar experimentellt arbete, analys och utvärdering av erhållna resultat samt skriftlig avrapportering. Laborationsassistent Rebecca Bejhed, tel , rum 4419, rebecca.sbejhedh@angstrom.uu.se Hemsida Examination Skriftlig tentamen fredag 18/3 Föreläsningsplan Tillfälle/sal Datum/Tid Ämne kapitel 1/Å /1, 8-10 Magnetiska fält, magnetisering... 1, /Å /1, 8-10 Avmagnetiserande fält, magnetiska kretsar, mätmetoder /Å /1, 8-10 Magnetiska material/egenskaper 3.7, 4, 6 4/Å /1, 8-12 Räkneövning 5/Å /1, 8-10 Magnetisk anisotropi/ , magnetostriktion , , 8.7 6/Å4007 3/2, 8-10 Domäner, domänväggar /Å6K1113 9/2, Räkneövning 8/Å /2, Magnetiseringsprocesser , /Å /2, 8-10 Mjukmagnetiska material 13 10/Å /2, 8-10 Räkneövning

2 11/Å /2, 8-10 Hårdmagnetiska material 14 12/Å4005 2/3, 8-10 Magnetiska lagringsmedia , 11.6, 15 13/Å4005 3/3, 8-10 Räkneövning 14/Å4003 8/3, Spinntronik föreläsningsartiklar, /Å /3, 8-10 Räkneövning 18/3 Tentamen Laborationsdagar: Fredag 11/2, Måndag 14/2, Tisdag 15/2, 9-12 Torsdag 17/2, Fredag 18/2, Projektdagar: Onsdag 16/2, Måndag 21/2, 8-12 Tisdag 22/2, 8-12 Projects One day of experimental work and evaluation of obtained results, as much time is spent on preparation by studying listed references and report writing. The report should be written as a scientific report including; i) abstract, ii) introduction including a brief description of studied materials, iii) description of performed experiments, iv) presentation of experimental results, v) discussion and conclusions, and vi) references. Magneto-Optical Kerr Effect (MOKE) Studies of magnetic anisotropy in thin magnetic films by use of MOKE. The films have been fabricated using UHV sputtering technique. The project will consist of the following parts: i) Literature study of MOKE ii) Tutorial on how to use the experimental MOKE equipment iii) Experimental recording of MOKE curves iv) Study of magnetic anisotropy of different thin films and/or multilayers Examples of questions to reflect on: Magnetic anisotropy in thin magnetic films can be of different origins; what contributions to the magnetic anisotropy may exist for thin films? How does the MOKE connect to the magnetization of the sample?

3 Reference: Z. Q. Qiu and S. D. Bader, Surface magneto-optic Kerr effect, Review of Scientific Instruments 71, (2000) Supervisor: Evangelos Papaioannou, Electromagnetic losses in soft magnetic materials Magnetic measurements on electrical steel (silicon-iron); the measurements will be performed (at Surahammars Bruk) on materials differing in sheet thickness and Sicontent and in an experimental setup called an Epstein frame. The energy loss per field cycle, calculated by integrating the measured hysteresis curve over one field cycle, for the different samples will be determined for different ac-field amplitudes and ac-field frequencies. From the measured total loss, you should be able to identify different contributions (hysteresis loss, eddy current loss and anomalous eddy current loss). Other magnetic parameters may also be studied. References: 1. G. Ban and G. Bertotti, J. Appl. Phys. 64 (1988) 5361; G. Bertotti, IEEE Trans. Magn. 24 (1988) A. Broddefalk and R. West, Dependence of the power loss of a non-oriented Sisteel on frequency and gauge, can be down-loaded from the course web-page. Supervisor: Arvid Broddefalk, Arvid.Broddefalk@sura.se Magnetic nanoparticles in carrier liquid magnetization dynamics Magnetic nanoparticles in biocompatible liquids have found numerous applications in bioscience, including magnetic bioseparation, targeted drug delivery, contrast agents in magnetic resonance imaging, etc. 1 In all cases, the response of the nanoparticles to a magnetic field plays an essential role, either by creating local magnetic fields or by being attracted to magnetic field sources. Magnetic nanoparticles can also be used in bioassay methods, where the presence or absence of a biological substance is revealed by the magnetic properties of the nanoparticles. In one particular scheme, the Brownian relaxation biosensor scheme, use is made of the dynamic magnetic response of the nanoparticles. In this project you will study the dynamic magnetic response of nanoparticles from Micromod 3 by performing ac magnetization measurements, 2 implying that you will investigate the response of the nanoparticles to a time varying magnetic field h0 cosωt. The measurement setup will allow you to vary the frequency ω of the time varying field, the amplitude h 0 of the field and the temperature of the nanoparticles. The measurements should be planned so that you can distinguish between i) Brownian and ii) Néel relaxation of magnetic nanoparticles. Examples of questions to reflect on: What are the desired properties of the magnetic nanoparticles in the Brownian relaxation biosensor method? What determines the magnetic dynamics of the nanoparticles in this

4 scheme? How can magnetic nanoparticles become biocompatible? What is the difference between magnetic nanobeads and magnetic nanoparticles? How would different carrier liquids change the dynamic magnetic response of the nanoparticles? Can you vary something in the experiment to go from Brownian relaxation to Néel relaxation using the same particles? References: 1. P. Svedlindh et al., Biomagnetism in Nanomagnetism and Spintronics (World Scientific Publishing Company Pte Ltd, Singapore (2008) 2. AC susceptibility application note from Supervisors: Rebecca Bejhed, and Peter Svedlindh, Permanent magnets without rare-earth element content - an experimental study of Fe 2 P 1-x Si x Permanent magnets are used in a wide range of demanding applications, including wind turbins, high performance generators and electric motors. Rare earth elements such as neodymium, praseodymium, samarium and dysprosium are important constituents in these magnets. However, there is an impending world-wide shortage of rare earth materials and most sources of raw rare earth materials are found in China. A common concern is the issue of being dependent on a few, limited sources of raw materials. The most investigated permanent magnetic materials are the rare earth based alloys (e.g. SmCo 5, Sm 2 Co 17 and Nd 2 Fe 14 B), FePt, CoPt and ceramic materials like hard ferrites. Concerning most of the important properties, the rare earth magnets are superior. The project will include an experimental study of the magnetic properties of Fe 2 P 1-x Si x. Fe 2 P is a rich magnetic system, basically ferromagnetic, which has been thoroughly studied since the seventies. Fe 2 P has a strong uniaxial anisotropy but a rather low transition temperature. However, substitutions as e.g. Si have strong impact on T c without drastically changing important properties such as the saturation magnetization. Fe 2 P has also been investigated as a promising refrigerant through the magnetocaloric effect. Some questions to reflect on: Which are the crucial parameters characterizing permanent magnets? How do we measure these parameters? What are the desired properties of permanent magnets?

5 What feature makes the Fe 2 P system a promising hard/permanent magnetic material? For an ideal permanent magnet, there are a few theoretical conditions to be fulfilled. Which are these? Are there other substitutional elements that could improve the hard magnetic properties of the Fe 2 P system? References: 1. J. M. D. Coey, J. Alloys Comp. 326, 2 (2001) 2. H. Fujii et al., J. Phys. Soc. Japan 43, 41 (1977) 3. R. Chandra et al., J. Solid State Chem. 34, (1980) 4. P. Jernberg et al., J. Solid State Chem. 53, (1984) 5. B. D. Cullity and C. D. Graham, Intoduction to magnetic materials, chapter 14 Supervisor: Klas Gunnarsson, room 4415, phone , klas.gunnarsson@angstrom.uu.se Projektarbete: Magnetfält i permanentmagnetiserade generatorer Handledare: Sandra Eriksson, avdelningen för elektricitetslära Uppgift: Att mäta och analysera magnetfältet i en permanentmagnetiserad generator. Bakgrund En permanentmagnetiserad generator har fördelen att man inte behöver elektromagneter i den roterande delen av generatorn, vilka har förluster samt kräver ett excitationssystem som överför elektricitet till den roterande delen. Det negativa är att generatorn är permanent magnetiserad, det vill säga man kan inte slå av fältet när så önskas. I det här projektarbetet ska magnetfältet i en labb-generator mätas upp och analyseras. Vidare ska de radiella magnetiska krafterna på lagren bestämmas. Projektuppgift Den magnetiska flödestätheten ska mätas i generatorns luftgap både i axiell, tangentiell och radiell riktning. Vidare ska läckflödet runt om generatorn bestämmas. På så sätt kommer en fullständig bild av magnetiska fältet i luftgapet och utanför generatorn att fås fram och analyseras. Vidare ska magnetfältet beräknas runt om generatorn för att kunna beräkna kraftdensiteten i luftgapet och den resulterande sidokraften på lagren i generatorn. I rapporten ska hela den magnetiska kretsen i generatorn beskrivas. Utrustning En 12 kw labbgenerator (se referens 1) Gauss/Teslameter (Sypris Model 7010) som mäter den magnetiska flödestätheten med hög noggrannhet.

6 Referenser 1. Sandra Eriksson, Andreas Solum, Mats Leijon and Hans Bernhoff, "Simulations and experiments on a 12 kw direct driven PM synchronous generator for wind power", Renewable Energy, Volume 33, Issue 4, April 2008, Pages K. Nilsson, O. Danielsson, and M. Leijon, "Electromagnetic forces in the air gap of a permanent magnet linear generator at no load", JOURNAL OF APPLIED PHYSICS 99, , 2006 Handledare Sandra Eriksson, Sandra.Eriksson@angstrom.uu.se, telefon