Observation of the second-order magnetic and reentrant spin-glass transitions in LiNi0.5Mn0.5O2

•Rietveld refinement confirms that the sample is a single phase with the rhombohedral layered structure.•Dc susceptibility data suggest a FiM transition at 108 K.•The results of Arrott method indication of the second-order character of the transition.•The ac susceptibility data confirm the SG transition in LiNi0.5Mn0.5O2 at 14 K.

The structure and magnetic properties of LiNi0.5Mn0.5O2 were studied by synchrotron X-ray diffraction, dc and ac susceptibilities. The material showed a continuous magnetic transition from paramagnetism into ferrimagnetism, followed by a spin glass with the decrease of temperature. Using a criterion given by Banerjee to distinguish first-order magnetic transition from second-order ones, it is shown that the ferrimagnetic transition at 108 K belongs to the second-order type. The frequency dependence of peak intensity and the shift in ac susceptibility at 14 K suggest a reentrant spin glass transition in LiNi0.5Mn0.5O2.