Magnetic properties of the In-doped MnWO 4 -type solid solutions Mn 1−3x In 2x □ x WO 4 [□=vacancy; 0≤ x ≤0.11]

Polycrystalline Mn1−3xIn2x□xWO4 (□=vacancy; 0≤x≤0.11) solid solutions synthesized via solid state reactions were characterized by means of magnetic ac susceptibility (χAC) and specific heat (C). The effect of this substitution on the magnetic transition temperatures give rise to three consequences: (1) the disappearance of the basic antiferromagnetic (AFM) phase AF1 when exceeding the doping concentration x=0.03; (2) the phase transition of the paramagnetic phase (PM) to the sinusoidal AFM phase AF3 at the Neel temperature (TN) is shifted toward lower temperatures with respect to pure MnWO4. This is valid also for the transition of AF3 to the cycloidal AFM phase AF2; (3) a systematic lowering of the effective magnetic moment with increasing In-doping. These substantial changes are attributed to the weakened overall magnetic interaction and a strong spin–lattice coupling due to the static disorder of Mn2+ with the nonmagnetic species, i.e. In3+ and vacancy.