Magnetoelastic coupling in Sr₂(Fe_1−xCr_x)ReO₆double perovskites

Abstract

We have investigated magnetoelastic coupling in Sr 2 (Fe 1−x Cr x )ReO 6 polycrystalline double perovskites. The end compound, Sr 2 CrReO 6 , shows a high ferromagnetic transition temperature of 635 K and is thought to exhibit a nearly half-metallic conduction band. We probed the unexpected high orbital moment borne by the Re atom by means of volume and anisotropic magnetostriction measurements in magnetic fields up to 12 T. Our magnetostriction results can be explained by the existence of a large spin-orbit coupling which, in combination with crystal-field effects, produces a singleion type magnetostrictive response. The Re orbital moment triggers a greatly enhanced magnetocrystalline anisotropy compared to other ferromagnetic double perovskites.From our magnetostriction data, the temperature dependence of the coercive field as a function of Cr-doping is obtained. We discovered that the coercive field increases as Fe is replaced with Cr, which is linked to a strong enhancement of the magnetic anisotropy. This suggests a close relationship between the Fe[Cr]-O-Re coupling and the magnetic anisotropy. We also analysed the impact of the Re orbital moment on the spin-dependent transport across Sr 2 CrReO 6 grain boundaries. The present work opens up the possible use of these compounds for magnetostrictive applications in a wide temperature and magnetic field range.

Charge ordering and magnetic properties in nanosized Sr2FeMoO6–δ powders

“…A manifold of magnetic states is observed in the Sr 2 FeMoO 6– δ (SFMO) half‐metallic ferrimagnet with the double perovskite structure, which is caused by the interplay between the orbital, charge, spin, and lattice degrees of freedom . The ferromagnetic structure is formed due to the ordering of the spins of the iron and molybdenum atoms in the Fe/Mo planes crossing each other under an angle of 120°.…”

Magnetoelasticity driven magnetic anisotropy changes in strainedSr2CrReO6

“…This interpretation is based on the magnetoelastic ͑ME͒ coupling, particularly because a giant anisotropic magnetostriction was previously experimentally found in Sr 2 CrReO 6 . 4 The observed effect can be quantitatively described by considering the part of the total energy density that depends on the magnetization direction ␣ ជ = ͑␣ 1 , ␣ 2 , ␣ 3 ͒. It includes the magnetic anisotropy f MA and the magnetoelastic f ME terms, which both obey the symmetry of the considered system.…”

“…The magnetic anisotropy originates from the SOC, which is stronger in heavier atoms therefore, the Re contribution must play the crucial role in the case of Sr 2 CrReO 6 . 4 In order to prove this assumption we performed an LSDA calculation with the SOC term included just for the Re atoms. As presented in the upper graph of Fig.…”

Structural, magnetic and electrical properties of a new double-perovskite LaNaMnMoO 6 material

“…The closer to t  = 1, the more the structure corresponds to ideal cubic. Therefore, except in rare cases, one can consider the following rule for the double-perovskite family: for 1.05 >  t  > 1.00, a cubic structure is adopted within the space group; for 1.00 >  t  > 0.97, the most likely structure corresponds to the I 4/m tetragonal space group and if t  < 0.97, the compound becomes either monoclinic ( P 21/ n ) or orthorhombic [31]. Table 3 shows the evolution of the tolerance factor of our sample LaNaMnMoO 6 and of its homologous double-perovskite oxide LaNaB′B′′O 6 /A 2 MnMoO 6 with different symmetry.…”