Theory of magnetic phases of hexagonal rare earth manganites

Abstract

The magnetic phases of hexagonal perovskites RMnO_3 (R=Ho, Er, Tm, Yb, Sc, Y) are analysed using group theory and the Landau theory of phase transitions. The competition between various magnetic order parameters is discussed in the context of antiferromagnetic interactions. A phenomenological model based on four one-dimensional magnetic order parameters is developed and studied numerically. It is shown that coupling of the various order parameters leads to a complex magnetic field-temperature phase diagram and the results are compared to experiment.Comment: 11 pages, 14 figures. Manuscript with higher quality figures can be obtained here: http://www.physics.mun.ca/~curnoe/papers/RMnO3.submit.pd