%0 Journal Article %T The underscreened Kondo effect in ladder systems %A Karyn Le Hur %J Physics %D 1999 %I arXiv %R 10.1103/PhysRevLett.83.848 %X We introduce a new Kondo ladder model by coupling the well-known Takhtajan-Babujan S=1 chain to a half-filled one-dimensional electron gas, and we solve it using quantum field theory techniques. Through the so-called underscreened Kondo effect, this gives novel insights into low-dimensional spin liquid systems. For instance, the optical conductivity reveals only a pseudogap at $k=\pi$ despite of the insulating state, a coherent magnon peak in the dynamical spin susceptibility coexists with an incoherent spinon background, the magnetization yields a fractional-like quantization. More generally, this problem belongs to the class of Luttinger liquids in active environments, a topic of importance not only to the Kondo physics, but also to striped phases or carbon nanotubes. Experimental consequences on heavy-fermion systems are also discussed. %U http://arxiv.org/abs/cond-mat/9906345v1