Antiferromagnetic resonance in single crystals of rhombohedral gadolinium ferroborate GdFe3(BO3)4 was studied. The frequency-field dependences of antiferromagnetic resonance over the frequency range 26–70 GHz and the temperature dependences of resonance parameters for magnetic fields oriented along the crystal axis and in the basal plane were determined. It was found that the iron subsystem, which can be treated as a two-sublattice antiferromagnet with anisotropy of the easy-plane type, experienced ordering at T=38 K. At temperatures below 20 K, the gadolinium subsystem with the opposite anisotropy sign strongly influenced the anisotropic properties of the crystal. This resulted in a spontaneous spin-reorientation transition from the easy-plane to the easy-axis state at 10 K. Below 10 K, magnetic field-induced transitions between the states were observed. Experimental phase diagrams on the temperature-magnetic field plane were constructed for fields oriented along the crystal axis and in the basal plane. A simple model was used to calculate the critical transition fields. The results were in close agreement with the experimental values measured at T=4.2 K for both field orientations. 相似文献
Physics of the Solid State - The structural, thermal, static magnetic, and resonance properties of the low-dimensional NaCuFe2(VO4)3 compound obtained by the solid-phase synthesis have been... 相似文献
Physics of the Solid State - Influence of the chemical pressure (x) in single crystals of FexMn1 – xS (0.12 ≤ x ≤ 0.29) on the spin state of iron ions was... 相似文献
The polycrystalline compound LiFeGe2O6 has been synthesized by the solid-phase reaction. The X-ray diffraction, Mössbauer, calorimetric, and magnetic investigations have been carried out. The Mössbauer spectrum at 300 K represents a single quadrupole doublet. The isomer shift with respect to the metal iron α-Fe is 0.40 mm/s, which is characteristic of the Fe3+ high-spin ion in the octahedral coordination. The quadrupole splitting of 0.42 mm/s indicates a distortion of the oxygen octahedron around the iron cation. The results of the measurement of the temperature dependence of the heat capacity in the range 2–300 K have shown the presence of the only anomaly with a maximum at Tm ~ 20.5 K, which indicates the occurrence of a magnetic phase transition in this point. The data of the measurement of the temperature dependence of the magnetization have confirmed that the magnetic order with the dominant antiferromagnetic interaction of magnetically active ions exists in LiFeGe2O6 at a temperature below 20.5 K. The investigation of the temperature dependence of the heat capacity in the magnetic field H up to 9 T has demonstrated that the external factor insignificantly changes the order-disorder transition point (at H = 9 T, there occurs a shift of ~0.5 K toward the low-temperature range).
The solid-phase synthesis in epitaxial Mn/Fe(001) bilayer film systems with 24 at % of Mn has been shown to start at a temperature of 220°C with the formation of a γ-austenite lattice and the Mn and Fe films react completely under annealing to 600°C. In the sample cooling process after annealing below 220°C, the γ austenite undergoes a martensitic transformation to an oriented ∈(100) martensite. When the annealing temperature is increased above 600°C, Mn atoms migrate from the γ-lattice, which becomes unstable, and the film is partially again transformed to the epitaxial Fe(001) layer. The solid-phase synthesis in Mn/Fe(001) bilayer nanofilms and multilayers is assumingly determined by the inverse ε → γ martensitic transformation in the Mn-Fe system. The existence of a new low-temperature (~220°C) structure transition in the Mn-Fe system with a high iron content is assumed. 相似文献
Single crystals of Pb2Fe2Ge2O9 have been grown. They were subjected to X-ray diffraction, magnetic, neutron diffraction, Mössbauer and spin resonance studies. It has been established that Pb2Fe2Ge2O9 is a weak ferromagnet with a Néel temperature TN = 46 K, and the exchange and spin-flop transition fields have been estimated. It has been demonstrated that the weak ferromagnetic moment is actually the result of the single-ion anisotropy axes for the magnetic moments of different magnetic sublattices being not collinear. 相似文献
High-quality CuCoAlBO5 single crystals have been grown, and their crystal structure, magnetic susceptibility, and magnetization have been studied.
It has been established that the CuCoAlBO5 compound is an uncompensated antiferromagnet or ferrimagnet with a small magnetic moment and the magnetic ordering temperature
TN = 28 K. A model has been proposed for the magnetic structure. A strong anisotropy of the magnetic properties has been revealed. 相似文献
The phase composition of iron films prepared by pulsed-plasma deposition in a controlled nitrogen atmosphere is investigated by Mössbauer spectroscopy. The observed changes in the phase composition are dictated by the nanocrystalline structure of the samples and the dynamics of the substrate temperature during film deposition. 相似文献
Ferrihydrite nanoparticles formed as a result of the microorganism activity have been studied using Mössbauer spectroscopy, X-ray powder diffraction analysis, and X-ray fluorescence analysis. Three positions of trivalent iron with nonoverlapping ranges of quadrupole splittings have been revealed in bacterial ferrihydrite: QS{Fe3+(1)} = 0.49–0.83 mm/s, QS{Fe3+(2)} = 0.84–1.10 mm/s, and QS{Fe3+(3)} = 1.25–1.73 mm/s. It has been experimentally demonstrated that the Fe3+(3) positions are the centers of nucleation of the hematite phase in the course of heat treatment. 相似文献
A new compound CuNaB3O6 · 0.842H2O was grown for the first time. Its crystal structure, magnetic susceptibility, and magnetic resonance properties are presented. It was proposed that CuNaB3O6 · 0.842H2O is a spin-Peierls magnet with the transition temperature TSP ~ 128 K and a ladder spin structure. The possibility of a structural phase transition at T < TSP is predicted. 相似文献