Spin reorientation behavior in YMn1-xMxO3 (M=Ti, Fe, Ga; x=0, 0.1)

The structural and magnetic properties of polycrystalline YMn1-xMxO3 (M=Ti, Fe, Ga; x=0, 0.1) have been studied by neutron powder diffraction and magnetic measurements to probe the effect of Mn site doping on the frustration behavior and magnetic structure of these compounds. The compounds are isostructural and crystallize with hexagonal structure in P6(3)cm space group. We find that doping with these three ions, Ti4+ (d(0)), Fe3+ (d(5)) and Ga3+ (d(10)), influences both the T-N and magnetic structure, unlike other Mn-site dopants reported previously. The magnetic structure of YMnO3 is described by considering a linear combination of irreducible representations Gamma 3 and Gamma 4 below T-N similar to 75 K and with decrease in temperature the ratio of Gamma 3 and Gamma 4 changes. The mixing ratio of these two irreducible representations remains constant on lowering of temperature in the Ga doped compounds. The magnetic structure is modified on doping with nonmagnetic ion Ti4+ (d(0)). It is described by the basis vectors of the irreducible representation Gamma 2 with moment 2.3(mu B) at 6 K. On doping with Fe3+ (d(5)) the magnetic structure immediately below T-N is explained by considering the Gamma 3 irreducible representation. On further lowering of temperature, a spin reorientation at similar to 35 K is observed. Below this temperature, the magnetic structure of YMn0.9Fe0.1O3 is explained by considering Gamma 3 representation with 51% mixing of Gamma 4. The ordered moments are found to be reduced from the expected value for a Mn3+ ion in all these compounds indicating the frustrated nature of these compounds. However, the frustration parameter, f is significantly reduced in the case of Ti doped compound with Gamma 2 representation. (c) 2013 Elsevier B.V. All rights reserved.