• 054348 - NANOMAGNETISM AND SPINTRONICS

The aim of this course is to present the fundamentals of micro and nanomagnetism necessary to understand the recent developments in the field of spintronics, thanks to a mix of lectures, exercices, informatic and experimental laboratories. In particular, a platform for micromagnetic simulation (OOMMF) will be presented, in order to provide the students with the essential tools for designing and analysing magnetic nano-devices. Experiments dealing with the characterization of magnetic materials and spintronic devices will be also carried pout with the participation of students. Finally, the lectures of the last part of the course are intended to review the recent advances in the field.

Knowledge and understanding

Upon passing the exam, the student:

- knows the principles of micromagnetism

- knows the basic analytical and computational approaches to calculate the micromagnetic configuration of a system

- knows the foundations of spintronics

- understands the structure and behaviour of conventional spintronic devices

- understands a scientific paper dealing with nanomagnetism and spintronics

Applying knowledge and understanding

Upon passing the exam, the student:

- is able to solve analytical problems connected to magnetism and spintronics

- is able to use a micromagnetic software (OOMMF) for the computation of static and dynamic micromagnetic configurations

- is able to design the basic structure of a spintronic device

Making judgements, Communication, Lifelong learning skills

Students who decide to prepare a project on micromagnetic simulation, as alternative to the written test:

- are able to model a real micromagnetic problem, identifying the relevant parameters and factors to be taken into account

- are able to solve a realistic problem and draw a general conclusion on the optimization work carried out via simulations

- are able to present their work in a report mimicking a scientific paper

- are able to communicate their work during the oral examination

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 the facility Polifab. Informatic laboratories connected to the usage of the micromagnetic platform OOMMF are also carried out woth the help of a tutor who will also assist students in the preparation of a project which can replace the written test.

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.

The examimation 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 the micromagnetic simulation and investigation of selected magnetic structures.

Good textbook on the fundamentals of magnetism and micromagnetisms

Reference text for micromagnetism

Reference text for Spintronics

Handbook of magnetism