ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
We discuss three applications of the overcompensated n-channel Kondo problem for an impurity of spin S =1/2 in the context of the exact numerical solution (as a function of field, temperature, and number of channels) of the Bethe-ansatz equations. The entropy has an essential singularity as H and T tend to zero, giving rise to critical behavior in the susceptibility and the specific heat. The specific heat in a small constant (nonzero) field shows a double peak structure, arising from the singularity in the entropy. This gives rise to giant γ values of the specific heat. The applications discussed here are (i) the quadrupolar Kondo effect, (ii) the low temperature properties of a two-level system interacting with conduction electrons, and (iii) a S =1/2 magnetic impurity embedded in a SU(2)-invariant Heisenberg chain of arbitrary spin (Takhtajan–Babujian model). The divergent quadrupolar susceptibility in (i) gives rise to a local tetragonal distortion of the lattice below a critical temperature Tc, which depends on the strength of the spin-lattice coupling. The same divergence destabilizes the low-temperature strong-coupling fixed point of (ii) for a symmetric double well.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.350143
