Field-induced incommensurate–commensurate phase transition of distorted-triangular-lattice antiferromagnet RbMn1−Fe Br3

Abstract Magnetic phase transitions of the distorted-triangular-lattice antiferromagnet RbMn 1− x Fe x Br 3 were studied using neutron diffraction experiments under magnetic fields. On weak doping of x ∼0.016, low-temperature crystal structure, zero-field Neel temperature, and zero-field incommensurate (IC) and field-induced commensurate (C) spin arrangements were found to be preserved. Nevertheless, at T=6.1 K , the crystal underwent the field-induced IC–C phase transition at a lower field of 2.3 T than the 3.1 T for pure RbMnBr 3 .