Spin order and entropy in antiferromagnetic films subjected to magnetic fields

Using systematic effective field theory, we explore the properties of antiferromagnetic films subjected to magnetic and staggered fields that are either mutually aligned or orthogonal. We provide low-temperature series for entropy density in case up two-loop order. Invoking staggered, uniform sublattice magnetizations bipartite antiferromagnet, investigate subtle order-disorder phenomena spin arrangement, induced by temperature, -- some which quite counterintuitive. In figures focus on spin-$\frac{1}{2}$ square-lattice but our results valid any other two-dimensional lattice.