Ing Ind - Inf (Mag.)(ord. 270) - BV (478) NUCLEAR ENGINEERING - INGEGNERIA NUCLEARE
097726 - NANOMAGNETISM AND SPINTRONICS
096075 - THIN FILMS: MAGNETISM AND SUPERCONDUCTIVITY
Ing Ind - Inf (Mag.)(ord. 270) - MI (486) ENGINEERING PHYSICS - INGEGNERIA FISICA
054854 - NANOMAGNETISM AND SPINTRONICS
054349 - MAGNETISM, SUPERCONDUCTIVITY AND SPINTRONICS (C.I.)
054853 - MAGNETISM AND SUPERCONDUCTIVITY
Ing Ind - Inf (Mag.)(ord. 270) - MI (491) MATERIALS ENGINEERING AND NANOTECHNOLOGY - INGEGNERIA DEI MATERIALI E DELLE NANOTECNOLOGIE
096075 - THIN FILMS: MAGNETISM AND SUPERCONDUCTIVITY
This course is composed of two parts: 1) on the generalities of magnetism and of superconductivity, 2) on micro and nano-magnetism and their application to spintronics. The two parts are held in parallel, following a detailed calendar provided at the beginning of the course.
Course 1) presents the two most important manifestation of ordering phenomena in solids: magnetism and superconductivity. The two are crucial for the understanding of the transport properties of crystalline materials, and can be exploited in a multitude of applications. Magnetism and superconductivity are governed by microscopic interactions, ultimately among electrons, but the macroscopic phenomenology is the result of interactions and dimensionality. The objective of the course is thus to provide a broad knowledge and understanding of ordering phenomena in solids. Phenomenology, experimental methods and theoretical models will be considered and confronted, with the aim of broadening the student's knowledge of ordering phenomena in solids and to underline how dimensionality influences them.
Course 2) presents the fundamentals of micro and nanomagnetism necessary to understand the recent developments in the field of spintronics. A platform for micromagnetic simulation will be also presented, in order to provide the students with the essential tools for designing and analysing magnetic nano-devices. Finally, lectures of the last part of the course are intended to review the recent advances in the field.
Risultati di apprendimento attesi
Lectures and exercise sessions will allow students to:
Know the fundamental concepts of ordering phenomena
Recognize the different types of magnetic order
Know the principles of micromagnetism and the foundations of spintronics
Know the general phenomenology of superconductivity
Determine which experimental methods can be used in the study of magnetism and superconductivity and, in general, of ordering phenomena in solids
Understand the structure and behaviour of conventional spintronic devices
Read and understand a scientific paper dealing with magnetism, superconductivity, nanomagnetism and spintronics
Apply knowledge and understanding to practical cases
Present a brief seminar on basic concepts and advanced examples on modern magnetism and superconductivity
Therefore, after passing the exam, the student will be able to:
DD1 - Understand the principles of magnetism and order phenomena, know the terminology related to them, employ the basic models applicable to them; know the principles of micromagnetism, the basic analytical and computational approaches to calculate the micromagnetic configuration of a system, the foundations of spintronics; understand the structure and behaviour of conventional spintronic devices; read and understand a scientific paper dealing with magnetism, superconductivity, nanomagnetism and spintronics
DD2 - Recognize analogue of magnetism and superconductivity in other contexts and apply models ant techniques in new contexts of physics and technology;be able to solve analytical problems connected to magnetism and spintronics, use a micromagnetic software (OOMMF) for the computation of static and dynamic micromagnetic configurations; be able to design the basic structure of a spintronic device
DD4 - Communicate her/his own perception of basic physics phenomena in a formal presentation
Moreover, a student who decides to prepare a project on micromagnetic simulation, as alternative to the written test, will be able to: - model a real micromagnetic problem, identifying the relevant parameters and factors to be taken into account - solve a realistic problem and draw a general conclusion on the optimization work carried out via simulations - present their work in a report mimicking a scientific paper - communicate their work during the oral examination
Magnetism of isolated magnetic moments Phenomenology: recalling diamagnetism, paramagnetism.
Atomic moments. Hunds rules Crystal field: origin of CF, quenching of orbital moments, Jahn-Teller effect.
Exchange interaction Examples of simple 3d transition metal oxides (NiO, MnO, Fe3O4) Perovskites Manganites and cuprates
Magnetic order and magnetic structures. Heisenberg and Ising models
Magnetism in metals Pauli paramagnetism Landau diamagnetism Stoner model RKKY interaction, Kondo effect
Excitations in magnetic systems Spin waves Stoner excitations
Magnetism at low dimensionality Spin chains and spin ladders 2 dimensional magnets Thin films
Superconductivity Phenomenology: transport, susceptibility, thermodynamics London equations Josephson effect Ginzburg-Landau model BCS theory Cuprate superconductors (also as an example of 2D antiferromagnets).
Experimental techniques. Magnetic resonances, Mössbauer spectroscopy, muon spin rotation. Elastic and inelastic scattering of neutrons and x-rays for magnetic structure and magnetic excitations. Magneto-optical techniques.
Nanomagentism is a modern discipline devoted to the study of magnetism in nanoscale objects. The "nano-world" opens unforeseen possibilities to develop new devices and paradigms exploiting the spin and orbital angular momentum of electrons and other quasi-particles (e.g. domain walls, magnons) propagating in engineered magnetic structures. Spintronics, in particular, is a branch of nanoelectronics aiming at developing new electronic devices taking advantage of the spin degree of freedom in addition to the charge of carriers. The program will consist of lectures and exercises devoted to these topics: - Micro and NANO magnetism - Demagnetizing field, magnetostatic energy. Landau magnetic free energy and its contributions (exchange, anisotropies, magnetostrictions). Domain walls. Micromagnetic simulations (OOMMF). Coherent magnetization reversal (Stoner Wohlfart model) and reversal via propagation of domain walls. Magnetic nanoparticles. Domain wall conduits. Magnetic coupling in multilayers (Néel coupling, Exchange bias, Bilinear coupling) MOTT-Spintronics - Two currents model and spin dependent scattering. Giant magnetoresistance in CIP and CPP configurations. Spin accumulation and Valet-Fert model. Tunneling magnetoresistance and magnetic tunneling junctions. Non volatile magnetic memories (MRAMs) and magnetic sensors. Spin transfer torque. Magneto-electric coupling. Spin injection, manipulation and detection in semiconductors. - Spinorbitronics. Rashba based devices and Spin-FET. Spin currents. Direct and inverse spin Hall effect. Antiferromagnet spintronics.
- LABORATORY ACTIVITIES: Laboratory instruction in specific techniques of magnetic characterization of materials and devices will be provided, at the laboratory of Nanomagnetism located within facility Polifab.
The program is designed for students of the Engineering Physics course, but also students from the electronic engineering, material science and nanotechnology courses may also benefit from this course. A good knowledge of the fundamentals of quantum mechanics and solid state physics is required, namely:
- General physics (in particular electromagnetism) - Quantum physics - Structure of matter and atomic physics - Advanced mathematical analysis and linear algebra - Solid state physics.
Modalità di valutazione
The two parts have independent exam and evaluations, that can be taken also in differnt "appelli".
The exam of Magnetism and Superoncductivity consists of two parts held during a single interview, in English.
1) A seminar of 20-25 minutes, on a subject pre-assigned by the teacher. The student has to present the general concepts of the theme in a correct and complete way, providing some examples at the level of the lectures and of the text book. The student is also invited to look for original examples, applications, interconnections with other subjects, to demonstrate a higher level of understanding. A powerpoint presentation is best suited for the seminar, but black/white board option is also possible.
2) Two or three questions on the core of the course as presented in the lectures. The student is requested to answer at the black/white board to show her/his understanding of the basic concepts and notions of the course. Theoretical and experimental aspects will be valued equally important.
A fully successful exam (27-30/30) will be deemed when a solid and broad mastering of the concepts of ordering phenomena in solids is demonstrated. An average grade (22-26/30) will be the result of fairly complete understanding of individual themes but with limited interconnection among subjects. A pass level (18-21/30) will correspond to a minimum knowledge of individual notions.
The examin of Nanomagnetism and spintronics is made of two parts:
(i) a written test (1 hour) with some exercises,
(ii) an oral examination. The written test can be replaced with a project on micromagnetic simulation and investigation of selected magnetic structures.
S. Blundell, Magnetismm in condensed matter, Editore: , Editore: Oxford University Press, ISBN: 978-0198505914
Harald Ibach , Hans Lüth, Solid-State Physics: An Introduction to Principles of Materials Science, Editore: Springer, ISBN: 978-3540938033
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