Competition of magnetic ordering and spin-phonon coupling in multiferroic hexagonal YMn1−xCrxO3.

Hexagonal yttrium manganite (YMnO₃) and chromium doped yttrium manganite (YMn_{1 – x}Cr_xO₃) were prepared by the solid-state method. X-ray diffraction and Raman scattering were combined to explore the structural characterization. Structural analysis illustrates that the lattice is compressed and the tilt of the MO₅ (M = Cr or Mn) bipyramid is decreased with an increase in Cr³⁺ concentration, leading to declining frustration. Magnetic measurement suggests both weak ferromagnetic (FM) and antiferromagnetic (AFM) orderings enhanced with the growth of doping concentration. Enhanced weak FM ordering may arise from breaking of the superexchange interaction and introduction of the double-exchange interaction inside the layers, and the increased AFM ordering is attributed to the improved coupling between neighboring planes that resulted from the structural distortion. Spin-phonon coupling is discussed to confirm the enhanced coupling between interplane Mn³⁺ moments. [ABSTRACT FROM AUTHOR]