Spin Electronics

1) Magnetoelectronics - positive magnetoresistance - negative magnetoresistance - anisotropic magnetoresistance - AMR (spin-orbit coupling and magnetic resistance) - Colossal magnetoresistance - CMR (manganates, Goodenough-Kanamori-Anderson rules, super and double exchange) - giant magnetoresistance - GMR (Oscillating exchange coupling, exchange anisotropy, artificial antiferromagnets, Intrinsic and extrinsic GMR) - Spin Valves - tunnel magnetoresistance - TMR (elastic tunneling through 1D barriers, conductor/ insulator /conductor, conductor/ insulator /superconductor contacts, ferromagnet / insulator / superconductor contacts, quasiparticles density of states in superconductors, density and spin polarization in ferromagnet ferromagnet / insulator / ferromagnet contacts and Julliere model, band structure effects, spin-filter) - Unusual magnetoresistance - EMR  2) spintronics - spin injection into semiconductors - spin-LEDs and spin-transistors 3) applications - XMR sensors - magnetoresistive read heads, hard drives - Magnetic Random Access Memory - MRAM 

After successful completion of this module, the student is able

1. to understand explain and compare magneto-Resisitive effects (anistrope magnetoresistance, colossal magnetoresistance, giant magnetoresistance, tunneling magnetoresistance)
2. to describe the magnetization and magnetoresistance curves of ferromagnetic layers and multilayers as a function of the magnetic field
3. to name elemental ferromagnets, some technically relevant soft and hard magnetic materials, as well as typical materials in magneto-electronic layer structures with the appropriate material parameters (Curie temperature, remanence, coercive field)
4. to calculate magnetoresistance effects with Boltzmann transport theory and tunneling theory in the one-dimensional limit
5. to describe ferromagnet / superconductor and ferromagnet / insulator / superconductor contacts 
6. to designate and analyze applications for magneto-resistive effects. 

No preconditions in addition to the requirements for the Master’s program in Physics.

The module consists of a lecture and an exercise.

In the thematically structured lecture the learning content is presented. With cross references between different topics the universal concepts in spinelectronics are shown. In scientific discussions the students are involved to stimulate their analytic-physics intellectual power.

In the exercise class the learning content is deepened and exercised using problem examples and simulations based on physical models. Thus the students are able to explain and apply the learned physics knowledge independently.

Talks, power point, presentation slides, excercises in groups and as an individual, discussions, online coursematerials, literature (textbooks and online materials)

• R. Gross & A. Marx, Vorlesungsskript Spinelektronik, Walther-Meissner-Institut, Garching (2005).
• S. Blundell, Magnetism in Condensed Matter, Oxford University Press, New York (2001).
• R.C. O'Handley, Modern magnetic materials - principles and applications, Wiley, New York (2000).
• D.D. Awschalom, D. Loss, N. Samarth (eds.), Semiconductor Spintronics and Quantum Computation, Springer, Berlin (2002).
• S. Maekawa (ed.), Concepts in Spin Electronics, Oxford University Press, New York (2006).
• Michael Coey: Magnetism and Magnetic Materials (Cambridge University Press, 2009).
• Y. Xu, D.D. Awschalom, J. Nitta, Handbook of Spintronics (Springer, 2016).

There will be an oral exam of 30 minutes duration. Therein the achievement of the competencies given in section learning outcome is tested exemplarily at least to the given cognition level using comprehension questions, discussions based on sketches and formulas.

For example an assignment in the exam might be:

• What are possible exchange coupling mechanisms between two ferromagnetic thin films?
• Which different scattering mechanisms give rise to the anomalous Hall effect in ferromagnets?
• What is the microscopic origin of the giant magnetoresistance effect?

In the exam no learning aids are permitted.

Participation in the exercise classes is strongly recommended since the exercises prepare for the problems of the exam and rehearse the specific competencies.