Structural transformation and magnetic competition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Yb</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi mathvariant="normal">Mn</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">Fe</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mo>)</mml:mo></mml:mrow><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Structural and magnetic properties of the $\mathrm{Yb}({\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x}){\mathrm{O}}_{3}$ $(0\ensuremath{\leqslant}x\ensuremath{\leqslant}1)$ system have been systematically investigated. Initial samples were prepared via a sol-gel method. A pure hexagonal phase was only obtained for samples with $x\ensuremath{\leqslant}0.5$. With high-pressure annealing, a pure orthorhombic perovskite phase was achieved for all the compositions. The $^{57}\mathrm{Fe}$ M\"ossbauer spectrum for $x=0.5$ shows that only ${\mathrm{Fe}}^{3+}$ ions exist in the system; there was no evidence of chemical inhomogeneities. With increasing $x$, the N\'eel temperature ${T}_{N}$ increases for both hexagonal and orthorhombic phases. The orthorhombic $\mathrm{Yb}({\mathrm{Mn}}_{0.5}{\mathrm{Fe}}_{0.5}){\mathrm{O}}_{3}$ shows an interesting weak ferromagnetic state in the temperature range of $239--298\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, the ferromagnetism disappearing abruptly on cooling below ${T}_{t}=239\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The transition at ${T}_{t}$ appears to be a reorientation of the spin axis of a type-$G$ antiferromagnetic order from the orthorhombic $a$ axis to the $b$ axis in the (010) plane.

Перевод пока недоступен