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Subject: MAGNETISM, SPINTRONICS AND QUANTUM TECHNOLOGIES (A.A. 2020/2021)

master degree course in PHYSICS – FISICA

Course year 1
CFU 6
Teaching units Unit Magnetism, spintronics and quantum technologies
Experimental and Applied Studies (lesson)
  • TAF: Compulsory subjects, characteristic of the class SSD: FIS/01 CFU: 6
Teachers: Marco AFFRONTE
Exam type oral
Evaluation final vote
Teaching language English
Contents download pdf download

Teachers

Marco AFFRONTE

Overview

Knowledge and understanding:
The course aims at providing the fundamentals of Magnetism: a) classical and quantum description to magnetic moments and their features; b) description of long range magnetic order and of magnetic phenomena at the nanoscale and at molecular and atomic level.
Basic experimental techniques and theoretical tools for understanding Magnetism will be illustrated.
The second part of the course is devoted to Fundamentals of Spintronics (Giant Magnetoresistance, Spin Valve, Spin Tranfer Torque, Spin devices) and to Quantum Technologies (Quantum sensing with Nitrogen vacancies, Superconducting qubits).

Applying knowledge and understanding:
The Physics of magnetic systems is proposed as prototypical for understanding: a) long range order; b) phenomena at the nanoscale, c) quantum states and interactions.
Fundamentals on Magnetism is finalized to understand the functioning of magnetic memories, spintronic devices, quantum computation and sensing.

Making judgments:
At the end of the course the student will be able to recognize on their own description of magnetic phenomena, magnetic memories and spintronic devices.

Communication skills:
At the end of the course the student will be able to report orally on the arguments presented in the course with a technical English.

Learning skills:
The study, carried out on transparencies and texts in English language, will enable the development of skills of independent learning and exploration of topical arguments in magnetism and spintronics.

Admission requirements

classical electromagnetism. modern physics

Course contents

1. Classical theory of magnetism in condensed matter:
Demagnetization factor.
The magnetic susceptibility: measurement techniques; typical trends.
2. Quantum theory of the magnetic moment:
Angular momentum and spin. g-factor.
isolated ion. Hund's rules.
Statistical mechanics and thermodynamic properties: partition function, susceptibility and specific heat, magnetocaloric effect.
Diamagnetism.
Paramagnetism: Curie law; formula of Van Vleck.
ion in a crystal field: d-f- metals
magnetic anisotropy.
3. Magnetic interactions:
exchange interaction, super-exchange, double exchange.
Spin Hamiltonians. Some special cases.
magnetism with free electrons. RKKY interaction.
4. Long-range order:
Mean field theory: the theory of Weiss (Neel). Molecular field.
Order parameter.
ferro-, antiferro-, iron-magnetism, other types of order. Spin glass.
Magnetic domains. Hysteresis loop. Coercive field. Hard & soft materials. Domain walls.
Exchange bias. (unidirectional anisotropy)
Domain wall & Spin logic.
5. Nano-magnetism.
Single-domain particle. Super-paramagnetism.
Nanoparticles & molecular magnets.
Stoner Wohlfarth model.
Landau-Lifschitz-Gilbert Model.
Neel-Brown model.
6. Magnetism in metals
Free electrons, the Pauli paramagnetism, spin split bands. 2-resistors model
Spin Injection and Accumulation at interfaces.
8. Spintronics devices.
Spin valve;
Giant Magneto Resistance.
Magnetic Random Access Memory.
spin torque
Spin transfer Oscillators
spin transistors
7. Dispositivi Spintronica.
Spin valve;
Giant Magneto Resistance.
Magnetic Random Access Memory.
Spin torque
Spin transfer Oscillators
Spin transistors

8. Quantum Technologies:
Cryogenics and Superconducting Magnets
Quantum Sensing with NV centers in diamond
Josephson junction besed devices
Superconducting qubits
9. Molecular magnetism: high-spin, low spin molecules
observation of quantum phenomena: tunnelling of magnetization.

Teaching methods

lectures experiments in the lab reading and presentation of scientific articles.

Assessment methods

oral test

Learning outcomes

The student will be able to understand basic magnetic phenomena, memories and logic devices

Readings

S. Blundell, "Magnetism in Condensed Matter" Oxford University Press.
Introduction to Solid State Physics, C. Kittel, Wiley.
Zutic, Fabian, and Das Sarma: “Spintronics: Fundamentals and applications” Rev. Mod. Phys., Vol. 76, No. 2, April 2004
E.Y. Tsymbal, Y. Zutic, Spintronics Handbook, Second Edition: Spin Transport and Magnetism: Vol 1 Metallic Spintronics 2019
S. Bandyopadhyay "Introduction to spintronics"CRC Press
T. Shinjo "Nanomagnetism and Spintronics" Elsevier 2009