Magnetic ordering effects in the random mixed one-dimensional ferromagnet-antiferromagnet system RbFeCl3-xBrx

Abstract

Elastic neutron scattering experiments were performed on single crystals of the solid solution RbFeCl3-xBrx (x=0.03, 0.06, 0.15, 1.0, 2.56, 2.76, 2.85 and 2.94) to study the magnetic ordering behaviour and the magnetic phase diagram of this mixed pseudo-one-dimensional ferromagnetic-antiferromagnetic system. Small amounts of dopant destroy the magnetic long-range order of the pure parent compounds, RbFeCl3 and RbFeBr3. On the RbFeCl3 side of the phase diagram the magnetic correlations appear finite for x as small as 0.03. The periodicities of these correlations are similar to those of the incommensurate and commensurate magnetic phases of pure RbFeCl3. On the RbFeBr3 side of the phase diagram the ordering vector remains at the H point (Q=(1/31/31)N). At an intermediate composition (x=1.0) there are no detectable one-dimensional ferro- or antiferromagnetic correlations down to a temperature of 1.3 K.