  We explore the behavior of the order parameter and the magnetization of
antiferromagnetic solids subjected to mutually parallel staggered and magnetic
fields. The effective field theory analysis of the partition function is taken
up to the two-loop level, where the magnon-magnon interaction comes into play.
These interaction effects, however, are small. A phenomenon that comes rather
unexpectedly is that the finite-temperature magnetization increases with
temperature when the strengths of the staggered and magnetic field are held
constant.
