• Alonso, José Antonio
• Céspedes, Eva
• Fernández-Díaz, Maria Teresa
• Martinez, José Luis
• Zhou, Jian-Shi
• Muñoz, Angel
• Gainza, Javier

Abstract

<jats:p>A polycrystalline sample LuCrO<jats:sub>3</jats:sub> has been characterized by neutron powder diffraction (NPD) and magnetization measurements. Its crystal structure has been Rietveld refined from NPD data in space group <jats:italic>Pnma</jats:italic>; this perovskite contains strongly tilted CrO<jats:sub>6</jats:sub> octahedra with extremely bent Cr—O—Cr superexchange angles of ∼142°. The NPD data show that below Néel temperature (<jats:italic>T</jats:italic><jats:sub>N</jats:sub> ≃ 131 K), the magnetic structure can be defined as an A-type antiferromagnetic arrangement of Cr<jats:sup>3+</jats:sup> magnetic moments, aligned along the <jats:italic>b</jats:italic> axis, with a canting along the <jats:italic>c</jats:italic> axis. A noticeable magnetostrictive effect is observed in the unit-cell parameters and volume upon cooling down across <jats:italic>T</jats:italic><jats:sub>N</jats:sub>. The AC magnetic susceptibility indicates the onset of magnetic ordering below 112.6 K; the magnetization isotherms below <jats:italic>T</jats:italic><jats:sub>N</jats:sub> show a nonlinear behaviour that is associated with the described canting of the Cr<jats:sup>3+</jats:sup> magnetic moments. From the Curie–Weiss law, the effective moment of the Cr<jats:sup>3+</jats:sup> sublattice is found to be μ<jats:sub>eff</jats:sub> = 3.55 μ<jats:sub>B</jats:sub> (calculated 3.7 μ<jats:sub>B</jats:sub>) while the Θ<jats:sub>CW</jats:sub> parameter yields a value of −155 K, indicating antiferromagnetic interactions. There is a conspicuous increase of <jats:italic>T</jats:italic><jats:sub>N</jats:sub> upon the application of external pressure, which must be due to shortening of the Cr—O bond length under compression that increases the orbital overlap integral.</jats:p>

Topics

• perovskite
• impedance spectroscopy
• susceptibility
• magnetization
• space group
• aligned