Metamagnetism and Weak Ferromagnetism in Nickel (II) oxalate crystals
  Microcrystals of orthorhombic nickel (II) oxalate dihydrate were synthesized through a precipitation reaction of aqueous solutions of nickel chloride and oxalic acid. Magnetic susceptibility exhibits a sharp peak at 3.3 K and a broadrounded maximum near 43 K. We associated the lower maximum with a metamagnetic transition that occurs when the magnetic field is about \geq 3.5 T. The maximum at 43 K is the typical of 1D antiferromagnets, whereas weak ferromagnetism behavior was observed in the range of 3.3 to 43 K. 
E Romero, ME Mendoza, R Escudero
cond-mat.mtrl-sci