TITOLO: MAGNETISMO NEI MATERIALI E MISURE MAGNETICHE

Codice corso: 01LDVKJ ANNO: 2014 DOTTORATO PROPONENTE: METROLOGIA: SCIENZA E TECNICA DELLE MISURE CREDITI : 4 DURATA (n. ore) 20 Docenti: Michaela Küpferling e Vittorio Basso, Istituto Nazionale di Ricerca Metrologica, Divisione Elettromagnetismo, Strada delle Cacce, 91, Torino, Italy ____________________________________________________________________ - Il corso si prefigge di introdurre i concetti di base per comprendere • il magnetismo nella materia ed in particolare il ferromagnetismo; • i processi di magnetizzazione nei materiali ferromagnetici di interesse nella tecnologia (i materiali dolci a basso campo coercitivo e alta permeabilità, i materiali duri ad alto campo coercitivo per magneti permanenti ed altre applicazioni come la registrazione magnetica) e • le tecniche sperimentali per la misura delle loro proprietà.

- Il corso si svolgerà nella sala riunioni del primo piano dell’edificio D dell’INRIM in Strada delle Cacce 91, Torino e si tiene in inglese.

- Il corso è aperto a tutti gli interessati. Chiunque intenda partecipare può inviare una e-mail di conferma a [email protected], [email protected], per rimanere aggiornato su eventuali cambiamenti.

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Magnetism, magnetic materials and measurements

- The aim of the course is to give an introduction to the basic concepts to understand • magnetism in magnetic materials and in particular ferromagnetism • the magnetization process in ferromagnetic materials for technological applications (soft magnetic materials with high permeability, hard magnetic materials with high coercivity, others, like magnetic recording media) •

Dates:

Mon/Lun the experimental techniques to measure the magnetic properties. - Place: Meeting room at the first floor of Building D, INRIM, Strada delle Cacce 91, Torino.

The lectures are in English.

- Interested students should send a confirmation email. to [email protected], [email protected], to be updated on last minute changes. ____________________________________________________________________ Tue/Mar Wed/Mer Thu/Gio Fri/Ven Sat/Sab Sun/Dom may 19 h10-12 L1 (MK) may 20 h10-12 L2 (VB) may 21 h10-12:30 L3 (MK) may 22 h10-12 L4 (VB) may 23 h10-12 L5 (MK) may 24 may 25 may 26 h10-12 L6 (VB) may 27 h10-12 L7 (VB) may 28 h10-12 L8 (MK) may 29 h10-12 L9 (VB) may 30 h10-11:30 L10 (MK) may 26 may 27

Program

(20 hours – 9 lectures)

Lecture 1 : Introduction to magnetism and magnetic materials (2 hours, MK) 1.1

1.2

1.3

Magnetism and technology: importance of magnetic materials Overview of the basic concepts of magnetism.

Orbital magnetic moment: Bohr magneton; diamagnetism.

Lecture 2 : Magnetism and Maxwell equations (2 hours, VB) 2.1

2.2

Magnetic media in Maxwell equations Magnetostatics Lecture 3 : Microscopic origin of magnetism (2 hours, MK) 3.1

3.2

Paramagnetism Ferromagnetism 3.2.1

Molecular field theory and Curie temperature 3.3

3.2.2

3.2.3

Spins and exchange Exchange in metals and oxides Antiferro- and Ferrimagnetism Lecture 4 : Energy terms of a ferromagnet (2 hours, VB) 4.1

4.2

4.3

4.4

4.5

Zeeman energy Magnetostatic energy Exchange energy Magnetic anisotropy and magnetoelastic effects Summary of magnetic energies Lecture 5 : Domains and domain walls (2 hours, MK) 5.1

5.2

5.3

5.4

5.5

Domain structures (closure domains, domains in thin films) Energy and width of domain walls Pinning and nucleation Single domain particle, Superparamagnetism Magnetooptics Lecture 6 : Magnetization processes (2 hours, VB) 6.1

Introduction: B-H curve and magnetization process 6.2

Macro- and Micro approach 6.2.1

Hysteresis modelling 6.3

6.2.2

Micromagnetics Magnetization dynamics Lecture 7 : Measurement techniques (2 hours, VB) 7.1

Generation and measurement of magnetic fields 7.1.1

Solenoids, Helmholtz coils, electromagnet, Halbach 7.1.2

Hall, NMR, pickup coils, Squid...

Lecture 8 : Soft magnetic materials (2 hours, MK) 8.1

General properties 8.1.1

Hysteresis loss, eddy current loss

8.2

8.1.2

Materials 8.2.1

Si-Fe, Fe-Ni, Fe-Co and Soft ferrites 8.2.2

Skin depth Amorphous materials 8.3

8.2.3

Magnetization measurements 8.3.1

Hysteresisgraph - wattmeter 8.3.2

Nanocrystalline materials Barkhausen noise measurement 8.3.3

Susceptibility: ballistic method Lecture 9 : Hard magnetic materials (2 hours, VB) 9.1

9.2

General properties (M-H, B-H, (BH) max ) Materials 9.2.1

Alnico 9.2.2

9.2.3

9.2.4

Hexagonal ferrites Rare Earth-Transition Metal Intermetallics Other 9.3

Magnetization measurements 9.3.1

Hysteresisgraph (hard material) 9.3.2

9.3.3

Vibrating Sample Magnetometer Pulsed field magnetometer (hard materials) 9.3.4

Anisotropy: torque measurement, SPD.

Lecture 10 : Special topics: Magnetoresistance and spintronics (2 hours, MK)

References:

F. Fiorillo,

Measurement and characterization of magnetic materials

, Elsevier, 2004.

G. Bertotti,

Hysteresis in Magnetism.

Academic Press, 1998 S. Blundell,

Magnetism in condensed matter

, Oxford University Press, 2001.

R. O'Handley,

Modern magnetic materials. Principles and applications

, John Wiley & Sons, 2000 B.D. Cullity,

Introduction to magnetic materials,

Addison-Wesley, 1972.

S. Chikazumi

Physics of ferromagnetism,

Oxford University Press, New York, 1997.

M.D. Coey,

Magnetism and magnetic materials

, Cambridge University Press, 2009.