Impact of rare earth magnetic moment on ordering of Ru in Sr2RuREO6 (RE   = Gd and Eu)
  We report synthesis and magnetization of Sr2RuREO6 (RE/Ru-211O6) with RE = Gd and Eu. Both Gd,Eu/Ru-211O6 are formed in distorted perovskite-type single phase with monoclinic P21/n space group. Magnetization (M/T) measurements exhibited antiferromagnetic ordering of Ru moments for both Gd and Eu compounds at TN of around 30 K due to super-exchange Ru-O-O-Ru interaction. Interestingly enough, detailed M/H plots of Gd/Ru-211O6 exhibited, the development of a ferromagnetic (FM) component at 20 K. Further at below 10 K, the FM component disappears and rather an spin freezing field (HSF) of around 1000 Oe is seen at 5 K. In case of Eu/Ru-211O6, the basic antiferromagnetic ordering of Ru moments remains invariant down to 5 K, and the appearance of FM component is not seen. It seems that the high magnetic moment of 8mB for Gd3+ influences the AFM ordering of Ru in case of Gd/Ru-211O6. 
V.P.S. Awana, Rahul Tripaathi, V.K. Sharma, H. Kishan (NPL, India), E.   Takayama-Muromachi (NIMS, Japan)and I. Felner (UNIV...