Structure and magnetism of copper substituted cobalt ludwigite Co₃O₂BO₃

The single crystals Co₃O₂BO₃ with partial (4%) substitution of Co by Cu ions were synthesized by the flux technique. X-ray diffraction and magnetic properties investigations were carried out. The x-ray diffraction meas-urements have shown that Cu clearly prefers only one from four nonequivalent crystallographic positions with the smallest electric field gradient. The ferrimagnetic ordering near TN = 43 K and high magnetic hardness in this magnetic phase are similar to Co₃O₂BO₃. The small reduction of the effective magnetic moment was revealed under copper substitution

Magnetic and resonance properties of multilayer (Gd/Si/Co/Si)ₙ films

Presented are the experimental investigation results of magnetic static and resonance properties of multilayer magnetic films in the system of 4f-3d elements separated by a semiconductor interlayer. Effects of temperature and magnetic field on interlayer coupling are detected. The role of the biquadratic exchange in formation of magnetic state in the whole system is established.Представлены результаты экспериментального исследования статических и резонансных магнитных свойств многослойных магнитных пленок в системе элементов 4f-3d, разделенных полупроводниковым промежуточным слоем. Обнаружено влияние температуры и магнитного поля на межслоевое взаимодействие. Установлена роль биквадратного обмена в формировании магнитного состояния системы как целого.Представлено результати експериментального досліджєння статичних та резонансних магнітних властивостей багатошарових магнітних плівок в системі елементів 4f-3d, розділених напівпровідниковим проміжним шаром. Виявлено вплив температури та магнітного поля на міжшарову взаємодію. Встановлено роль біквадратного обміну у формуванні магнітного стану системи як цілого

Antiferromagnetic ordering in REM cobaltite GdCoO 3

Temperature and magnetic-field dependences of the static magnetization of polycrystalline cobaltite GdCoO 3 have been measured. The magnetic properties of the GdCoO 3 sample have been studied in the paramagnetic and antiferromagnetic states. The magnetic phase diagram has been constructed. The exchange field between the Gd-Gd sublattices and the anisotropy field have been estimated. Zapotitlán 2012 Pleiades Publishing, Ltd

Electron spin resonance in Cu1 xFexCr2Se4 nanoparticles synthesized with the thermal decomposition method

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.In this paper, we present a study of the electron spin resonance (ESR) of nanoparticles (NPs) of Cu1 xFexCr2Se4 chalcogenides with x = 0, 0.2, and 0.4. NPs were synthesized via the thermal decomposition of metal chloride salts and selenium powder in a high-temperature organic solvent. According to the XRD and HRTEM data, the NPs were single crystalline nearly hexagonal plates with the structure close to CuCr2Se4 (Fd-3m, a = 10.337 Å). For x = 0 and 0.2, the NPs tend to form long stacks consisting of the plates ‘‘face to face” attached to each other due to the magnetostatic interparticle interaction. Only separate NPs were observed in the case of x = 0.4. Peculiarities were revealed in the ESR temperature behavior for the NPs with x = 0 and 0.2 consistent with the features in the temperature dependences of the NPs magnetization. The non-monotonous dependence of the resonance field Hres on the temperature with a kink near 130 K and the energy gap in the resonance spectrum depending on the type of nanoparticle compacting are the distinct peculiarities. One of the main factors is discussed in order to explain the peculiarities: the coexistence of two types of anisotropy in the Cu1 xFexCr2Se4 NPs, in-plain shape anisotropy and magnetocrystalline anisotropy with four easy axes, which increases strongly with the temperature decrease

Electron spin resonance in Cu1 xFexCr2Se4 nanoparticles synthesized with the thermal decomposition method

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.In this paper, we present a study of the electron spin resonance (ESR) of nanoparticles (NPs) of Cu1 xFexCr2Se4 chalcogenides with x = 0, 0.2, and 0.4. NPs were synthesized via the thermal decomposition of metal chloride salts and selenium powder in a high-temperature organic solvent. According to the XRD and HRTEM data, the NPs were single crystalline nearly hexagonal plates with the structure close to CuCr2Se4 (Fd-3m, a = 10.337 Å). For x = 0 and 0.2, the NPs tend to form long stacks consisting of the plates ‘‘face to face” attached to each other due to the magnetostatic interparticle interaction. Only separate NPs were observed in the case of x = 0.4. Peculiarities were revealed in the ESR temperature behavior for the NPs with x = 0 and 0.2 consistent with the features in the temperature dependences of the NPs magnetization. The non-monotonous dependence of the resonance field Hres on the temperature with a kink near 130 K and the energy gap in the resonance spectrum depending on the type of nanoparticle compacting are the distinct peculiarities. One of the main factors is discussed in order to explain the peculiarities: the coexistence of two types of anisotropy in the Cu1 xFexCr2Se4 NPs, in-plain shape anisotropy and magnetocrystalline anisotropy with four easy axes, which increases strongly with the temperature decrease

Effects of processing parameters on the morphology, structure, and magnetic properties of Cu1−xFexCr2Se4 nanoparticles synthesized with chemical methods

Cu1−xFexCr2Se4 nanoparticles with x = 0, 0.2, and 0.4 were synthesized via thermal decomposition of metal nitrate or chloride salts and selenium powder using different precursor compositions and processing details. Single crystalline nano-belts or nano-rods coexist in the synthesized powder samples with hexagon-shaped plates in dependence on the precursor composition. The belts gathered into conglomerates forming “hierarchical” particles. Visible magnetic circular dichroism (MCD) of Cu1−xFexCr2Se4 nanoparticles embedded into a transparent matrix was investigated for the first time. The similarity of the MCD spectra of all samples showed the similarity of the nanoparticles electronic structure independent of their morphology. Basing on the MCD spectral maxima characteristics, electron transitions from the ground to the excited states were identified with the help of the conventional band theory and the multi-electron approach