Anant K. Ramdas

Anant K. Ramdas, a pioneer in condensed-matter physics, passed away peacefully on 22 November 2024. He is survived by his wife of 68 years, Vasanti, his sisters Vijaya Ramnath and Rajalakshmi Ram, and brother L. R. Ram-Mohan.

Anant was born on 19 May 1930, in Pune, India. He received his BSc degree in 1950, his MSc degree in 1953, and his PhD degree in 1956, all from Poona University. The latter two degrees were conducted at the Raman Research Institute under the guidance of Nobel laureate C. V. Raman. Thereafter, Anant joined the physics department of Purdue University as a research associate in 1956 and spent the balance of his professional career there rising to hold the Lark-Horovitz Chair of Physics.

Along with his colleagues Peter Fisher and Sergio Rodriguez, Anant pioneered the study of the spectroscopy of impurity states in semiconductors using infrared transmission and Raman scattering techniques under ambient and enhanced pressure at low temperature. His application of piezo modulation to semiconductor quantum heterostructures led to the most precise determination of energy levels, for both bound and quasi-bound states. Anant is also renowned for his application of Zeeman, electro-, and piezo-spectroscopies to the study of the optical properties of classic crystalline solids such as ruby, quartz, and diamond. His work on the latter is one of his most cited papers. Using Brillouin and Raman scattering, Anant also investigated the isotopic variation of elastic constants of semiconductors. Together with his collaborators Rodriguez and T. R. Anthony and students M. Grimsditch, R. Vogelgesang, and Hyunjung Kim, Anant showed that carbon-13 has larger elastic constants than carbon-12, thereby making it the hardest material available!

For his contributions to our fundamental understanding of the physical and optical properties of solids, especially facilitated by the application of group theory, Anant was the recipient of numerous honors and awards. These included the Frank Isakson Prize of the American Physical Society in 1994, the Raman Centenary Medal in 1988, and the Alexander von Humboldt Senior US Scientist Award in 1977–78.

His abiding interest in group theory profoundly influenced all who interacted with him. Among his most lasting contributions to the physical sciences, in addition to those noted above, were his skill as a classroom teacher of both graduate and undergraduate physics and, especially, his nurturing and guidance of his doctoral and postdoctoral students, in whom he instilled the valuable trait of self-critical objectivity.

Anant Ramdas will be sorely missed by all who knew, loved, and respected him. His passing constitutes a major loss not only to his many colleagues, students, and collaborators, but also to science and to the subfield of condensed-matter physics.

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