Reversal magnetization, spin reorientation and exchange bias in YCrO$_3$ doped with praseodymium

摘要

Crystal structure, thermal and magnetic properties were systematicallystudied in the Y$_{1-x}$Pr$_x$CrO$_3$ with $0 \leq x \leq 0.3$ compositions.Magnetic susceptibility and specific heat measurements show an increase of theantiferromagnetic transition temperature ($T_N$) as Pr is substituted in the Ysites and notable magnetic features are observed below $T_N$. Strong couplingbetween magnetic and crystalline parameters is observed in a small range of Prcompositions. A small perturbation in the lattice parameters by Pr ion issufficient to induce a spin reorientation transition followed by magnetizationreversal, to finally induce exchange bias effect. The spin reorientationtemperature ($T_{SR}$) is increased from 35 K to 149 K for $0.025 \leq x \leq0.1$ compositions. It is found that the Cr spins sublattice rotatescontinuously from $T_{SR}$ to a new spin configuration a lower temperature. Inaddition, magnetization reversal is observed at $T^* \sim 35$ K for x= 0.05 upto $T^* \sim 63$ K for x = 0.20 composition. The $M-H$ curves show negativeexchange bias effect induced by Pr ions, which are observed below of 100 K andbeing more intense at 5 K. At 10 K, the magnetic contribution of the specificheat, as well as the ZFC magnetization, show the rise of a peak with increasingPr content. The magnetic anomaly could be associated with the freezing of thePr magnetic moment randomly distributed at the 4c crystallographic site. Aclear correspondence between spin reorientation, magnetization reversal andexchange bias anisotropy with the tilting and octahedral distortion is alsodiscussed.