Two- and three-dimensional magnetic ordering in the bilayer manganite Ca2.5 Sr0.5 GaMn2 O8

Abstract

Neutron diffraction study as a function of temperature on the bilayered manganite Ca2.5 Sr0.5 GaMn2 O8 has revealed antiferromagnetic correlations between the [010] oriented Mn spins in the a-c plane. Three-dimensional (3D) short-range and two-dimensional (2D) long-range order over the temperature ranges 180-170 K and 165-160 K, respectively, have been observed. Below ∼150 K, a pure 3D long-range ordering has been observed. Finally a phase diagram is proposed. A qualitative connection is made between the 2D and 3D magnetic ordering to the transport and magnetotransport properties reported for this system. © 2006 The American Physical Society.