The next time you listen to your iPod/MP3 player or use a memory stick to transfer files you should thank Albert Fert and Peter Grünberg who discovered Giant Magnetoresistance (or GMR) in the 1980’s.
Were it not for this, hard drives and memory sticks/cards could not be as small as they are today
Nearly 20 years later, they were awarded the Nobel Prize in Physics for independent discoveries leading to the same conclusion published in November 1988 and in March 1989 respectively.
It was a discovery ahead of it’s time which probably explains the time period between discovery and the prize being awarded.
Fundamental to the phenomenon is RKKY (Ruderman-Kittel-Kasuya-Yosida) interaction
H represents the Hamiltonian, Rij is the distance between the nuclei i and j, Iij is the nuclear spin of atom i, Δkmkm is a term that represents the strength of the hyperfine
It’s all rather nasty quantum mechanics – but in fact this interaction discovered in the 1950’s predicted what was to become GMR
