Global Stability and the Magnetic Phase Diagram of a Geometrically-Frustrated Triangular Lattice Antiferromagnet...

While a magnetic phase may be both locally stable and globally unstable, global stability always
implies local stability. The distinction between local and global stability is studied on a
geometrically-frustrated triangular lattice antiferromagnet with easy axis, single-ion anisotropy D
along the z axis. Whereas the critical value Dloc
c for local stability may be discontinuous across a
phase boundary, the critical value Dglo
c  Dloc
c for global stability must be continuous. We demonstrate
this behavior across the phase boundary between collinear 3 and 4 sublattice phases that are
stable for large D.