Quasi-Kondo phenomenon due to the dynamical Jahn-Teller effect.

A mechanism of the nonmagnetic Kondo effect is proposed on the basis of a multiorbital Anderson model coupled with dynamical Jahn-Teller (JT) phonons. An electron system coupled dynamically with JT phonons has a vibronic ground state with double degeneracy due to clockwise and anticlockwise rotational modes with entropy of log2. When a temperature is lower than a characteristic energy to turn the rotational direction, the rotational degree of freedom is eventually suppressed and the corresponding entropy is released, leading to quasi-Kondo behavior. We discuss a simple relation between the "Kondo" temperature and the JT energy.