Exact Solution of the Simplest Superorthosymplectic Invariant Magnet.

We present the exact solution of the Osp(1|2) invariant magnet by the Bethe ansatz approach. The associated Bethe ansatz equation exhibit a new feature by presenting an explicit and distinct phase behaviour in even and odd sectors of the theory. The ground state, the low-lying excitations and the critical properties are discussed by exploiting the Bethe ansatz solution.