Docentship lecture: Listening to the Quantum Echoes of Magnetism

Chairperson: professor Olle Eriksson

Representative of the Docentship Committee: professor Carlos Pérez de los Heros

Abstract:

Magnetism surrounds us in countless ways, from the compass needle that guided early explorers to the powerful magnets used in today’s advanced technologies. Yet beneath this familiar phenomenon lies a rich and fascinating quantum world.

In this lecture, we will journey into the microscopic origins of magnetism, exploring how the collective behavior of countless quantum spins gives rise to the magnetic properties we see at the macroscopic scale. We will examine how interactions between spins lead to magnetic domains and derive the fundamental equations that describe domain walls, the boundaries where these regions meet and compete.

Finally, theory will meet experiment as we bring the invisible dance of magnetic domains to life through the Barkhausen effect. By listening to the tiny, crackling "quantum echoes" produced when domain walls suddenly shift, we will transform abstract equations into tangible sound.

This lecture blends physics, mathematics, and direct sensory experience to reveal how the quantum nature of magnetism manifests itself in the real world—sometimes in ways you can truly hear.

The lecture is an obligatory teaching test for those applying for admittance as docent and it should be possible for students and others with basic academic education in the relevant field to follow it. The lecture lasts 40-45 minutes with subsequent discussion. The lecture will be given in English.