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Dipartimento di Fisica e Scienze della Terra


Why Magnetism?


Magnetism is at the root of a number of technological applications encountered in everyday life:

Electric motors exploit the force that permanent magnets exert on electric currents. In this animation of a stepping motor N and S represent the North and South poles of an array of permanent magnets, attached to the rotating axle. Injection of currents of appropriate directions (red and blue indicate opposite directions for the flowing currents) produce successive steps of the motor rotation.

(Animation from http://www.cs.uiowa.edu/~jones/step/) .

Magnetic recording in the form of magnetic tape is perhaps not so common anymore for music and videos, but the ability to impose the direction of North and South poles of tiny portions of a magnetic film is also the heart of digital data storage in computers (the hard disks), where it supports the encoding of any type of information, from taxt databases, to music, videos, scientific computation, etc. The Magnetic Force Microscope image on the right (by M. Ghidini and Lodi Rizzini) shows these bits as rectangles delimited by dark and light stripes indicating the position of their North and South poles on the surface of the disk.

And, of course, the magnet's most vital function: on the front door of your refrigerator! (credit: S. Blundell, Magnetsm, Oxford, OUP 2001)

Improving ALL these applications is actually the task of engineers. The task of a physics and material science laboratory is to try and push forward the search for new materials and new effects, without the immediate aim of a new commercial product. The explored routes sometimes give rise to new answers to technological problems, other times do not. Unfortunately it is extremely difficult to predict which will, and the only working approach is to be driven by (wise) curiosity. Wisdom requires that potential technological spin-off is always considered. Curiosity suggests to widen the forefront of the investigation.