DC-magnetization measurements on electrochemically delithiated

The magnetism of electrochemically delithiated Lix[Ni1/2Mn3/2]O4 samples with space group P 4 3 32 has been studied by dc-magnetization measurements. For the x = 1 sample, the temperature ( T ) dependence of the magnetization/field ( = M / H ) showed the appearance of a spontaneous magnetization below 130 K. Moreover, since a clear ferromagnetic (FM) M – H loop was observed at 5 K and its saturated magnetization ( M s ) was almost equivalent to the predicted value ( = 3.5 μ B ), the whole sample was found to enter into a FM phase below 130 K ( = T C ) . A very similar FM behavior was also obtained for the x = 0.5 sample below 130 K, while the magnitude of M s was almost a half of that for the x = 1 sample. In contrast to the x = 1 and 0.5 samples, M for the x = 0.05 sample increases almost linearly in the H range between ∼5 and 55 kOe. Therefore, it is found that the fully delithiated Lix[Ni1/2Mn3/2]O4 sample is in a paramagnetic or antiferromagnetic state even at 5 K.