Spintronics : basics and applications

PHYS-510 / 4 crédits

Enseignant(s): Pivetta Marina, Rusponi Stefano

Langue: Anglais

Summary

Starting from fundamentals of magnetism, the course develops the concepts required to understand and describe reading and writing processes of a magnetic bit. Similarities and differences between classical and quantum systems are addressed.

Content

Spintronics is one of the emerging fields focused on next-generation nanoelectronic devices aiming at reduced power consumption and increased memory and processing capabilities. Such devices use not only the electron charge, as traditional electronics does, but also the electron spin as an additional degree of freedom to boost performance. The course provides the basis necessary to understand and describe spin dynamics in solids and nanostructures. The time evolution of the magnetization under the torque generated by magnetic fields and spin currents is presented. Applications to devices as hard disk drive (HDD) and magnetic random-access memory (MRAM) are discussed. Finally, analogies and differences of spin dynamics in 3D/2D vs 0D (single atom bit) materials are shown.

 

1) Fundamentals of magnetism
- Magnetic moments (spin and orbital moment, Hund's rules)
- Spin-orbit interaction
- Exchange interactions (Heisenberg exchange, Dzyaloshinskii-Moriya interaction (DMI))
- Crystal field and magnetic anisotropy


2) Spin dynamics in solids and nanostructures
- Magnetization dynamics induced by magnetic fields and temperature
- Continuum approximation: Landau-Lifshitz-Gilbert (LLG) equation and its microscopic origin
- Bit reversal: coherent vs incoherent reversal
- Designing and writing the recording media in HDD

3) Spin transfer torque (STT)
- Giant (GMR) and tunnel (TMR) magnetoresistance, magnetic tunnel junctions (MTJ)
- Writing by means of spin-polarized currents: Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation
- GMR/TMR for reading heads in HDD, and for MRAM operation

4) Spin orbitronics
- Spin-orbit torque (SOT) at interfaces (Rashba-Edelstein effect, spin-Hall effect (SHE))
- SOT- MTJ vs. STT- MTJ: opportunities and challenges for devices

5) From continuum approximation to quantum dynamics
- Quantum tunneling of magnetization
- Single atom magnets and single ion molecular magnets
- Demagnetization induced by spin-phonon and spin-electron scattering
- Writing and reading single atom magnets with spin-polarized currents: spin polarized scanning tunneling microscopy (SP-STM)
- Single atom magnets as qubit prototypes

 

 

Keywords

spin, magnetoresistance, magnetization dynamics, qubits, magnetic anisotropy, exchange

Learning Prerequisites

Recommended courses

Basic knowledge in atomic and solid state physics is helpful

Learning Outcomes

By the end of the course, the student must be able to:

  • Formulate the laws describing the macrospin dynamics of a classical magnetic bit
  • Formulate the laws describing the spin dynamics of a qubit
  • Assess / Evaluate the effect of a spin current on the magnetic state of a bit
  • Interpret the results of a scientific experiment

Transversal skills

  • Use a work methodology appropriate to the task.
  • Demonstrate the capacity for critical thinking
  • Summarize an article or a technical report.

Teaching methods

Ex cathedra with exercises in class

Assessment methods

Oral exam

Resources

Bibliography

1)      Spintronics: fundamental and applications; P. Dey and J. N. Roy, Springer 2021

2)      Introduction to spintronics; S. Bandyopadhyay and M. Cahay, CRC Press 2015

3)      Spintronics: A Primer; J. P. Ansermet, CRC Press 2024

 

Ressources en bibliothèque

Moodle Link

Dans les plans d'études

  • Semestre: Printemps
  • Forme de l'examen: Oral (session d'été)
  • Matière examinée: Spintronics : basics and applications
  • Cours: 2 Heure(s) hebdo x 14 semaines
  • Exercices: 2 Heure(s) hebdo x 14 semaines
  • Type: optionnel
  • Semestre: Printemps
  • Forme de l'examen: Oral (session d'été)
  • Matière examinée: Spintronics : basics and applications
  • Cours: 2 Heure(s) hebdo x 14 semaines
  • Exercices: 2 Heure(s) hebdo x 14 semaines
  • Type: optionnel
  • Semestre: Printemps
  • Forme de l'examen: Oral (session d'été)
  • Matière examinée: Spintronics : basics and applications
  • Cours: 2 Heure(s) hebdo x 14 semaines
  • Exercices: 2 Heure(s) hebdo x 14 semaines
  • Type: optionnel
  • Semestre: Printemps
  • Forme de l'examen: Oral (session d'été)
  • Matière examinée: Spintronics : basics and applications
  • Cours: 2 Heure(s) hebdo x 14 semaines
  • Exercices: 2 Heure(s) hebdo x 14 semaines
  • Type: optionnel
  • Forme de l'examen: Oral (session d'été)
  • Matière examinée: Spintronics : basics and applications
  • Cours: 2 Heure(s) hebdo x 14 semaines
  • Exercices: 2 Heure(s) hebdo x 14 semaines
  • Type: optionnel

Semaine de référence

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