  In this brief review, we introduce a new spin ladder system called skewed
spin ladders and discuss the exotic quantum phases of this system. The spin
ladders studied are the 5/7, 3/4 and 3/5 systems corresponding to alternately
fused 5 and 7 membered rings; 3 and 4 membered rings; and 3 and 5 membered
rings. These ladders show completely different behaviour as the Hamiltonian
model parameter is changed. When the Hamiltonian parameter is increased the 5/7
ladder switches from an initial singlet ground state to progressively higher
spin ground state and then to a reentrant singlet state before finally settling
to the highest spin ground state whose spin equals the number of unit cells in
the system. The 3/4 ladder goes from a singlet ground state to a high spin
ground state with each unit cell contributing spin 1 to the state, as the model
parameter is increased. The 3/5 ladder shows a singlet ground state for small
parameters and high spin ground state for intermediate values of the parameter
and for still higher parameters, a reentrant singlet ground state. They can
also show interesting magnetization plateaus as illustrated by studies on a
specific spin ladder.
