k=0Magnetic Structure and Absence of Ferroelectricity inSmFeO3

Abstract

SmFeO3 has attracted considerable attention very recently due to its reported multiferroic properties above room temperature. We have performed powder and single crystal neutron diffraction as well as complementary polarization dependent soft X-ray absorption spectroscopy measurements on floating-zone grown SmFeO3 single crystals in order to determine its magnetic structure. We found a k=0 G-type collinear antiferromagnetic structure that is not compatible with inverse Dzyaloshinskii-Moriya interaction driven ferroelectricity. While the structural data reveal a clear sign for magneto-elastic coupling at the Néel-temperature of ∼675 K, the dielectric measurements remain silent as far as ferroelectricity is concerned.

Interplay of Fe and Tm moments through the spin-reorientation transition inTmFeO3

“…For 3d transition-metal ions these techniques are very sensitive in the soft-x-ray regime and a number of different coupled magnetic transition-metal oxide systems have been already studied in the past by both XMCD and resonant x-ray-diffraction techniques [13][14][15][16][17]. In orthoferrites, XMCD and XMLD have been used to characterize the magnetic ordering phenomena of the Fe sublattice, or its interaction with other magnetic layers grown on it [18][19][20][21][22].…”

Structure Peculiarities of Micro- and Nanocrystalline Perovskite Ferrites La1−x Sm x FeO3

“…At the ambient conditions, both LaFeO 3 and SmFeO 3 display the orthorhombic perovskite structure isotypic with GdFeO 3 [14, 15]. In situ high-resolution X-ray synchrotron and neutron powder diffraction examination revealed no structural changes in SmFeO 3 in the temperature range of 300–1173 K [16], whereas LaFeO 3 undergoes the first-order orthorhombic-to-rhombohedral structural phase transition at 1253–1260 K [17–19]. Lattice expansion of LaFeO 3 and SmFeO 3 shows non-linear and strongly anisotropic thermal behaviour: in both compounds relative expansion in b -direction is much lower than in a - and c -directions [16, 18–20].…”

“…As a result, lattice parameter crossovers occur in LaFeO 3 at 750–950 K [18–20]. Subtle anomalies in the lattice expansion detected in LaFeO 3 and SmFeO 3 are associated with antiferromagnetic—to paramagnetic phase transition occurred in these compounds at 735 and 670 K, respectively [11, 12, 16, 21]. In LaFeO 3 , such anomalies are reflected in non-linear lattice expansion across the magnetic phase transition at the Néel temperature 735 K [18] and in the step of dilatometric thermal expansion coefficient at 723 ± 50 K. In SmFeO 3 , the b parameter exhibits a small anomalous kink around 670 K that is indicative for magnetoelastic coupling at the magnetic ordering temperature T N [16].…”

Raman spectroscopy of rare-earth orthoferrites RFeO3 ( R =La, Sm, Eu, Gd, Tb, Dy)

“…In contrast to the Fe 3+ cations, the magnetic moments of the R 3+ rare earth ions order below 10 K. Interestingly, a so-called compensation point where moments of the two sublattices cancel has been reported for several RFeO 3 compounds [1]. More recent studies have also focused on spin-ordering processes of the rare earth ions [4][5][6] and the interaction between magnetism and crystal lattice, including the role of spin-lattice coupling in multiferroic properties [7][8][9][10][11].…”