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| Home > Publications database > Mysterious incommensurate Dy3+ magnetic ordering in DyFeO3. Spherical neutronpolarimetry study |
| Home > Publications database > Mysterious incommensurate Dy3+ magnetic ordering in DyFeO3. Spherical neutronpolarimetry study |
| Poster (Invited) | FZJ-2024-06884 |
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2024
Abstract: DyFeO3 is the only known rare-earth orthoferrite with an incommensurate magnetic ordering ofthe rare-earth element without an external magnetic field [1,2]. DyFeO3 establish the ordering ofthe Fe3+ sublattice, according to the Γ4 representation (magnetic space group Pb′n′m) below TN= 645 K. Below the spin-reorientation temperature TSR ≈ 65 K magnetic moments rotate into theΓ1 (Pbnm.1) Fe3+ structure with symmetry forbidden ferromagnetic component, making it suitablefor spherical neutron polarimetry studies.Our unpolarized single crystal neutron diffraction (IN12, ILL) measurements show the temperatureevolution of DyFeO3 satellites at zero magnetic field below 4 K [3]. It is worth comparing it withTbFeO3 [4] which orders incommensurately in a solitonic lattice in the applied magnetic field (~ 3K and H > 1 T). Both show long modulation periods (DyFeO3 280 Å and TbFeO3 340 Å) and higherorder satellites (DyFeO3 up to 7th order, TbFeO3 up to 11th order). However, in DyFeO3 the intensityratio between satellites suggests triangular modulation (1/n2), while for TbFeO3 it is square-like (1/n),where n is the satellite order. DyFeO3 and TbFeO3 have different modulation vector directions, [00l]and [0k1], respectively. The formations of incommensurate order in DyFeO3 and TbFeO3 are offirst-order and second-order type, respectively.The incommensurate magnetic order of Tb3+ in TbFeO3 is reported as the solitonic lattice [4], whilefor Dy3+ magnetic ordering in DyFeO3, three models are proposed in the literature: (i) spin densitywave [1], (ii) elliptical-based helical ordering [1], and (iii) spin density wave on the top of commensurateordering [2]. Our half polarization analysis on DyFeO3 [3] shows no magnetic chirality termand our spherical neutron polarimetry analysis supports the spin density wave ordering model overthe helical ordering model (both measured on TASP, PSI). Surprisingly, we observed a high valueof the Pxz component of the polarization matrix measured on magnetic satellite peaks, in contradictionwith all models proposed in the literature [1,2]. According to the Blume-Maleev equations,the Pxz component arises from nuclear-magnetic interference, however, high values of the Pxz termwere observed for (001)±q and (003)±q satellite peaks, which are pure magnetic as (001) and (003)commensurate peaks are nuclear-forbidden. Spherical neutron polarimetry data were collected veryrecently and we are working on the model of the Dy3+ magnetic ordering in DyFeO3.[1] C. Ritter, et al.; J. Phys.: Condens. Matter 34 (2022) 265801; [2] B. Biswas, et al.; Phys. Rev. Mater.6 (2022), 074401; [3] Under preparation; [4] S. Artyukhin, et al.; Nat. Mater. 11 (2012) 694
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