Honeycomb-lattice antiferromagnet Mn2V2O7: a temperature-dependent x-ray diffraction, neutron diffraction and ESR study

Temperature-dependent x-ray diffraction (XRD), neutron powder diffraction and high-field electron spin resonance (ESR) have been employed to study the structural and magnetic properties of distorted honeycomb lattice Mn2V2O7. The XRD data reveal that upon cooling Mn2V2O7 undergoes a martensitic-like β–α structural phase transition at ~270 K. Upon heating, however, the reversible α–β structural transition takes place at ~210 K, showing the first-order feature of the transition. The temperature range, where the two phases coexist, is well determined. With further decrease in temperature, a paramagnetic-to-antiferromagnetic (AFM) phase transition takes place at TN = ~23 K as indicated by ESR and neutron powder diffraction data. The ESR data demonstrate the AFM resonance modes below TN, which can be well understood by conventional AFM resonance theory with uniaxial anisotropy.