Alladi Ramakrishnan Hall

Exotic Physics of 4f electrons

E. V. Sampathkumaran

HBCSE, TIFR, Mumbai.

The rare-earth based materials have been attracting considerable attention from the basic science and applications angle for the past several decades. From the basic science angle, the rare-earths with a tendency for multiple valency (Ce, Sm, Eu, Tm and Yb) have been considered to be exciting due to some degree of 4f-delocalization (leading to “heaviness” of electrons). However, the magnetic and transport behavior of other rare-earths, particularly heavy rare-earth compounds with “stable valence”, had been considered uninteresting, due to the localized nature of 4f orbital inhibiting participation in chemical bonding and hence had not been paid enough attention by physicists. Our studies have shown that even such rare-earths present puzzling situations, revealing new concepts in solids. Thus, entire rare-earth series present exotic physics in modern condensed matter physics area, which will be outlined with a few examples in this talk.