GdMnO3β shows an incommensurate antiferromagnetic order below β42
K, transforms into a canted A-type antiferromagnet below β20 K, and for
finite magnetic fields along the b axis ferroelectric order occurs below
β12 K. From high-resolution thermal expansion measurements along all
three principal axes, we determine the uniaxial pressure dependencies of the
various transition temperatures and discuss their correlation to changes of the
magnetic exchange couplings in RMnO3β (R=La,...Dy).Comment: 2 pages, 3 figures, submitted to JMMM (Proceedings of ICM'06, Kyoto