John Michael David Coey (1945-2025) was one of Ireland's most distinguished physicists and a global authority on magnetism with a career spanning over five decades. Born in Belfast, he studied at Cambridge University before completing his PhD at the University of Manitoba in Canada in 1971. He held research positions at CNRS in Grenoble and IBM's T.J. Watson Research Center before joining Trinity College Dublin in 1978, where he became Professor of Physics in 1987 and was appointed to the prestigious Erasmus Smith's Professorship of Natural and Experimental Philosophy from 2007 to 2012. Throughout his career, Coey maintained extensive international collaborations across Europe, North America, and Asia, establishing himself as a leading figure in the global physics community.
Coey authored over 700 scientific publications on diverse aspects of magnetism, including the highly regarded textbook "Magnetism and Magnetic Materials," which has become a standard reference in the field. His research spanned fundamental investigations of magnetic phenomena in amorphous and natural materials to the development of novel permanent magnets with practical applications. He pioneered research on "d⁰ ferromagnetism," exploring magnetic properties in materials without conventional 3d or 4f moments, which he aptly termed "fickle ferromagnetism" due to its defect-related and sometimes unstable nature. With an H-index of 116 and over 74,000 citations, his work has had profound influence across physics, materials science, and engineering disciplines worldwide.
Beyond his research, Coey played a transformative role in Ireland's scientific landscape by founding Magnetic Solutions Ltd. in 1994 and co-establishing CRANN (the Centre for Research on Adaptive Nanostructures and Nanodevices) in 2002, which grew into a world-leading nanoscience research hub. He conceived Dublin's innovative Science Gallery in 2006, demonstrating his commitment to public engagement and science communication. As a dedicated educator, he mentored generations of students at Trinity College Dublin and remained actively involved in undergraduate teaching until shortly before his death. His legacy endures through CRANN's continued research excellence, the ongoing impact of his scientific contributions, and the inspiration he provided to physicists around the globe.
