An interplay between Kondo screening and magnetic frustration may lead to novel phases of matter and exotic excitations. Also, a number of corresponding heavy fermion materials exist, such as YbAl3C3 and CeAgBi2.
As an example I have studied a 1D spin ladder model with a nonmagnetic valence bond solid (VBS) ground state in the presence of conduction electrons and magnetic field. I have shown that the critical field for the transition is suppressed by Kondo coupling, and novel phenomena, such as SDW gap phase (shown in green) or sign-changing superconductivity may occur. Results of the analytical predictions have been shown to be in excellent agreement with DMRG calculations.