Allan Roy Mackintosh, FRS[1] (22 January 1936 – 20 December 1995) was a prominent Danish physicist and a leading authority on magnetism and neutron scattering, especially in the rare-earth metals.
His doctoral research at Cambridge was carried out in the renowned Cavendish Laboratory under Sir Brian Pippard, where he investigated the Fermi surface of metals.
During a 1966 sabbatical at the Riso National Laboratory in Denmark, Mackintosh discovered a technique to quantify the magnetic moments on an atomic scale using the newly constructed neutron spectrometer.
His measurements of the spin waves in rare-earth metals marked a significant advance in the study of magnetism, for which he was awarded (jointly with Hans Bjerrum Møller) the prestigious Spedding Prize in 1986.
Long known for his careful yet lucid prose, Mackintosh's publication in 1991, with Jens Jensen, of Rare Earth Magnetism, was a landmark in solid state physics and the book became a classic text.