Quantum Hall Solitons with Intertwined Spin and Pseudospin at $\nu =1$

In this paper we study in detail different types of topological solitons which are possible in bilayer quantum Hall systems at filling fraction $\nu =1$ when spin degrees of freedom are included. Starting from a microscopic Hamiltonian we derive an effective energy functional for studying such excitations. The gauge invariance and $C{P}^3$ character of this energy fuctional and their consequences are examined. Then we identify permissible classes of finite energy solutions which are topologically non-trivial. We also numerically evaulate a representative solution in which a pseudospin (layer degrees of freedom) bimeron in a given spin component is intertwined with spin-skyrmions in each layer, and and discuss whether it is energetically favoured as the lowest lying excitation in such system with some numerical results.