Study of short range correlations and two-fold spin reorientation in NdFe0.5Mn0.5O3

摘要

Detailed powder neutron diffraction studies as a function of temperature is performed on NdFe0.5Mn0.5O3 in the temperature range 400-1.5 K. Diffused magnetic scattering is observed due to three dimensional short range ordering (SRO), between Fe3+/Mn3+ spins, over the whole temperature range 400-1.5 K. The presence of SRO is independent of long range ordering (LRO) in this compound which has never been observed in any Fe3+/Mn3+ based compounds. Further, in this compound two-fold spin reorientation is discussed in the temperature range 300-1.5 K. Development of long range ordering at 300 K is due to the mixture of Gamma(4) and Gamma(1) magnetic structure, not like other orthoferrites which have Gamma(4) structure at 300 K. This occurs due to the presence of large single ion anisotropy of Mn3+ ions. Volume fraction of Gamma(4) decreases with temperature leading to pure Gamma(1) magnetic structure in the temperature range 150-90 K. Another spin reorientation of Fe3+/Mn3+ spins occurs from Gamma(1) to Gamma(2) in the temperature range 70-25 K.