Investigation of spin-orientation in antiferromagnetic ordering for LiFe1-xZnxPO4 with Mössbauer spectroscopy

We have investigated the spin orientation in antiferromagnetic polycrystalline LiFe1-xZnxPO4 using Mössbauer spectroscopy. The temperature-dependent magnetic susceptibility curves show antiferromagnetic behavior with ordering temperature. The experimentally determined effective moment of LiFe1-xZnxPO4 is larger than the theoretical value, which can be explained as incomplete absence of orbital contribution by the crystalline field around distorted octahedra. The value of the Néel temperature (TN) and the spin reorientation temperature (TS) of LiFe1-xZnxPO4 decreased with the increasing Zn concentrations from 48 and 14 K for x = 0.1 to 36 and 8 K for x = 0.5, resulting in weak antiferromagnetic interaction. Below TN, Mössbauer spectra of LiFe1-xZnxPO4 showed asymmetric eight-line shape due to the strong crystalline field in the distorted octahedral structure. A change in both the magnetic hyperfine field and electric quadrupole splitting below TS suggests that magnetic phase transition is related to the spin rotation and the superexchange interaction.