The obituaries are the first thing I read every month when I get a new issue of Physics Today. I find them to be a highly personal and fascinating way to become acquainted, albeit loosely, with historical developments in widely ranging topics in physics through the eyes of the deceased’s colleagues. However, I must express some confusion regarding the back-to-back obituaries, in the October 2001 issue, of Clifford Glenwood Shull (page 86, written by Ralph Moon and Robert J. Birgeneau) and Louis Néel (page 88, written by Jacques Friedel). When one reads both obituaries at the same sitting, it becomes clear that the scientific paths of these two men crossed during the course of their lives, but one is left confused as to the specifics.
The Shull obituary explains that among Cliff’s accomplishments with neutron diffraction were that the “first direct evidence of antiferromagnetism came from determining the magnetic structure of manganese oxide” and that the “Néel model of ferrimagnetism was confirmed for magnetite.” The ensuing Néel obituary describes how Néel in fact “developed the concept of antiferromagnetism” along with predicting susceptibility peaks at the “Néel temperature.” Then, a somewhat confusing paragraph mentions contributions from Lev Landau and Cornelius Gorter to the theory of “antiferromagnetism,” but these are apparently irrelevant for certain materials that involve a “magnetic wall of high energy.” Without further clarification, that paragraph ends with this: “Using neutron diffraction, Harry Shull confirmed (in 1950) Néel’s model.”
First, who is Harry Shull? Second, just what did he confirm in 1950? The proposals about the Néel temperature were “made in 1936 … [and] confirmed in 1938 on manganese oxide,” according to Néel’s obituary. Shull’s obituary, in which he is consistently called “Cliff,” says that Shull confirmed antiferromagnetism in manganese oxide, presumably after 1938 (after the “war ended”) and confirmed the Néel model for ferrimagnetism for magnetite, probably around 1950, as I interpret it.
I hope you can you see my confusion. Maybe people used to call Cliff “Harry.” Maybe the development of the theory of “antiferromagnetism” for manganese oxide is so related to the theory of “ferrimagnetism” for magnetite that distinctions about what “Harry” confirmed, and when and how, are not so important.
