Crystalline and magnetic structures, magnetization, heat capacity, and anisotropic magnetostriction effect in a yttrium-chromium oxide

摘要: We have studied a nearly stoichiometric insulating ${\mathrm{Y}}_{0.97(2)}{\mathrm{Cr}}_{0.98(2)}{\mathrm{O}}_{3.00(2)}$ single crystal by performing measurements of magnetization, heat capacity, and neutron diffraction. Albeit that the $\mathrm{Y}\mathrm{Cr}{\mathrm{O}}_{3}$ compound behaves like soft ferromagnet with coersive force $\ensuremath{\sim}0.05$ T, there exist strong antiferromagnetic (AFM) interactions between ${\mathrm{Cr}}^{3+}$ spins due to strongly negative paramagnetic Curie-Weiss temperature, i.e., $\ensuremath{-}433.2$(6) K. The coexistence ferromagnetism antiferromagnetism may indicate canted AFM structure. phase transition occurs at ${T}_{\text{N}}=141.5(1)\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, which increases ${T}_{\text{N}}$(5 T) = 144.5(1) K 5 T. Within accuracy present neutron-diffraction studies, we determined G-type structure propagation vector k (1 1 0) spin directions along crystallographic $c$ axis orthorhombic space group $Pnma$ below ${T}_{\text{N}}$. At 12 K, refined moment size is 2.45(6) ${\ensuremath{\mu}}_{\text{B}}, \ensuremath{\sim}82%$ theoretical saturation value $3\phantom{\rule{0.28em}{0ex}}{\ensuremath{\mu}}_{\text{B}}$. are probably two-dimensional Ising within reciprocal scattering plane. Below ${T}_{\text{N}}$, lattice configuration ($a$, $b$ , $V$ ) deviates largely downward from Gr\"uneisen law, displaying an anisotropic magnetostriction effect magnetoelastic effect. Especially, sample contraction upon cooling enhanced temperature. There evidence suggest actual crystalline symmetry lower than currently assumed one. Additionally, compared ${t}_{2\text{g}}\phantom{\rule{4pt}{0ex}}\mathrm{Y}\mathrm{Cr}{\mathrm{O}}_{3}$ ${e}_{\text{g}}\phantom{\rule{4pt}{0ex}}{\mathrm{La}}_{7/8}{\mathrm{Sr}}_{1/8}{\mathrm{MnO}}_{3}$ crystals for further understanding reason possible lowering.