Gen Shirane

Gen Shirane, one of the world’s foremost authorities on using neutron scattering as a probe of solids, and who for more than half a century was a leader in developing techniques by which high-flux nuclear research reactors were transformed into premier tools for studying condensed matter physics, died of a stroke at his home in Bellport, New York, on 16 January 2005.

Born in Nishinomiya, Japan, on 15 May 1924, Gen received a bachelor’s degree in engineering physics from the University of Tokyo in 1947 and worked briefly at the Tokyo Institute of Technology. In the evolving society of post—World War II Japan, he was impatient with the old hierarchical ways of Japanese science; even before receiving his PhD in science from the University of Tokyo in 1954, he set off for Pennsylvania State University, where he worked from 1952 to 1957. His early experiments at Penn State and Tokyo used x-ray scattering, and his scientific interests were in symmetry-breaking phase transformations in ferroelectric materials and in the materials’ resulting piezoelectric and nonlinear optical properties. During this period he coauthored with Franco Jona a book on ferroelectricity that is a classic reference still used by workers in the field.

In 1957 Gen moved to Westing-house Research Laboratories in Pittsburgh, Pennsylvania, and his interests broadened to include magnetic materials, the newly discovered Mössbauer effect, and neutron diffraction. The neutron-scattering experiments were carried out mostly at the graphite reactor at Brookhaven National Laboratory. One of Gen’s first experiments there was pioneering work with Robert Nathans, Clifford Shull, and Arne Andersen that demonstrated an important method for producing polarized neutrons.

Gen moved permanently to Brookhaven in 1963, as the Brookhaven High Flux Beam Reactor construction was being completed, and he contributed to the development of a suite of experimental instruments. The increased neutron flux made possible inelastic neutron-scattering experiments using the triple-axis spectrometer developed by Bertram Brockhouse in Canada. Optimizing the signal-to-noise ratio in these instruments is an art form in which Gen quickly established himself as a virtuoso, and that expertise led ultimately to his publication, with co-authors Stephen Shapiro and John Tranquada, of the definitive monograph on that subject.

Although his ability to tease signals out of noisy data was phenomenal, it was not his most impressive talent. He had an unerring sense of where neutrons could make a difference in the understanding of the physics of materials and how to develop the techniques needed to perform the requisite experiments, and an ability to attract the collaborators most able to help attack these critical problems. In the 1970s his collaborations led to pioneering studies of low-dimensional magnetic systems, and somewhat later to low-dimensional structural phase transformations as well. Those studies illuminated the increased importance of fluctuations in lower-dimensional systems. Gen was principally responsible for an in-house effort that confirmed the soft-mode theory of structural phase transformations in a variety of systems and discovered previously unenvisioned features, such as interpenetrating incommensurate lattices.

In Gen’s body of work, which includes nearly 700 published papers, a further unifying thread involves the properties of superconductors. He performed the first neutron-scattering experiments to show the effect of a superconducting energy gap on phonon linewidths, a key prediction of Bardeen-Cooper-Schrieffer theory. But perhaps the pinnacle of Gen’s distinguished career involves his studies in the late 1980s and early 1990s of high-temperature superconductors. All of his experience in perovskite-like structures, magnetism, lower-dimensional phenomena, and superconductivity came together beautifully in that series of experiments. He and his collaborators performed seminal studies of the magnetic fluctuations in both the insulating parent materials and their superconducting counterparts. He also re-turned to the use of × rays at the National Synchrotron Light Source, combining those experiments with neutron scattering to further the attempts at understanding these materials. While there is not yet a consensus on the detailed mechanism of high-temperature superconductivity, Gen’s results provide a crucial foundation for the common belief that antiferromagnetic correlations play a fundamental role.

Gen was very aware that society had entrusted him with an expensive research tool, and he felt personally responsible for seeing that it was used productively. He was unapologetic in his belief that he was a better judge of the merits and probable success of proposed research than a more egalitarian user committee would be. The productivity of the neutron-scattering group at Brookhaven was unsurpassed under his leadership and provides substantial support for his view.

His early emigration notwithstanding, Gen retained an intense interest in Japanese science. He established strong and continuing collaborations between US and Japanese researchers, and through example and constant mentoring he promoted rapid recognition and advancement of younger Japanese scientists.

Gen’s scientific achievements have been recognized with a series of honors, including the Warren Award of the American Crystallographic Association (corecipient, 1973), and the Buckley Prize of the American Physical Society (1973). He was inducted into the National Academy of Sciences in 1989 and the American Academy of Arts and Sciences in 1991.

Personally responsible for training an entire generation of neutron scatterers, he is remembered as a stern taskmaster. Ernest Rutherford was said to have once remarked, “I do not let my boys waste their time.” Gen would have concurred and added, “Or waste neutrons either.” He once said to one of us, “There are only two experiments that matter—the first and the best. And the ultimate is when they are both the same.” Nothing less than superior science was ever acceptable to him. Perhaps his most lasting legacy is the many scientists who struggled to meet his exacting standards and who now populate elite research centers worldwide. It falls to them to recall and pass along to a new generation some of Gen’s enthusiasm, dedication, and passion for both science and life.