Long Range and Short Range Magnetic Order in Orthorhombic LiMnO2

Abstract The magnetic properties of orthorhombic LiMnO 2 have been investigated in detail for the first time. The susceptibility data show several features including a Curie–Weiss regime from 600 to 800 K with θ p =−1056(13) K and μ eff =4.82 μ B /Mn 3+ , a broad maximum at 360 K, and a field-cooled (FC), zero field cooled (ZFC) divergence below 100 K. The broad maximum indicates two-dimensional rather than one-dimensional short-range spin correlations. A Neel temperature for a transition to three-dimensional long-range order is seen at 261.5 K from both neutron diffraction and the magnetic heat capacity behavior as determined from the susceptibility data. The magnetic structure has been solved from neutron diffraction data and has a propagation vector of k =(1/2 1/2 1/2) and an ordered magnetic moment of 3.69(4) μ B /Mn 3+ with a preferred direction parallel to the b axis. The neutron scattering data also provide evidence for two-dimensional short-range correlations above T c at 271 K in the form of a feature with a Warren line shape. The long- and short-range order are discussed in terms of the crystal structure which is of the ordered NaCl type distorted by the presence of the Jahn–Teller ion, Mn 3+ .