V.I. Tugarinov

Electron spin resonance in CuCrS2 chrome-copper disulphides synthesized by different methods

The electron spin resonance (ESR) in CuCrS2 disulphides is found to be strongly dependent on a synthesis method used. At a temperature of 300 K, a polycrystalline CuCrS2 sample is paramagnetic with a g-value of 1.95 at 40 K, it undergoes the magnetic transition. In the temperature range 4.2–290 K, a single-crystal sample prepared by a chemical vapor transport method exhibits the ESR features typical of a ferromagnet. It is shown that these features are related to the presence of a small amount of the single-crystal CuCr2S4 impurity in the CuCrS2 single crystal.

Structural and magnetic resonance investigations of CuCr2S4 nanoclusters and nanocrystals

Nanoclusters and nanocrystals of the room temperature magnetic spinel CuCr2S4 synthesized using a facile solution-based method have been examined by transmission electron microscopy, magnetic measurements, and magnetic resonance over a wide frequency range 9.6–80u2009GHz and at temperatures down to 4.2u2009K. Decreasing of the resonance field and broadening of the resonance lines below 50u2009K for both samples are due to the freezing of magnetic moments of nanocubes and nanocrystalline particles constituting nanoclusters. The effective fields of averaged magnetic anisotropy ⟨HA⟩≅ 2.4 kOe are similar for both nanopowder samples as estimated from resonance measurements at Tu2009=u20094.2u2009K. An additional blocking temperature Tb ≅ 300u2009K appears in nanoclusters due to freezing of the magnetic moment of the entire cluster as a whole. Below this blocking temperature, the magnetic dipolar field acting in boundary areas of interacting constituent nanocrystals is responsible for the additional low-field resonance line observed in th...

Magnetic Resonance in a Cu-Cr-S Structure

A layered Cu-Cr-S structure composed of single-crystal CuCrS2 layers and thin CuCr2S4 plates embedded in them has been investigated by the magnetic resonance and scanning electron microscopy methods. The Curie temperature and saturation magnetization of the spinel phase of the investigated samples have been determined. The thickness of the CuCr2S4 layers has been estimated. The dependence of the growncrystal topology on synthesis conditions has been established. An interpretation of the anomalous behavior of the magnetostatic oscillation intensity is offered.

Magnetic-resonance and thermophysical studies of the magnetic phase diagram for a GdFe2.1Ga0.9(BO3)4 single crystal

The antiferromagnetic resonance, heat capacity, magnetic properties, and magnetic phase diagram of a GdFe3(BO3)4 crystal in which some of the iron ions were substituted by diamagnetic gallium ions have been investigated. It has been found that the Neél temperature upon diamagnetic substitution decreased to 17 K compared to 38 K in the unsubstituted crystal. The effective exchange and anisotropy fields for GdFe2.1Ga0.9(BO3)4 have been estimated from the field dependences of magnetization and resonance measurements. The magnetic phase diagram of the crystal has been constructed from magnetic and resonance measurements. In GdFe2.1Ga0.9(BO3)4, there is no spontaneous reorientation and, in the absence of a magnetic field, the crystal remains an easy-axis one in the entire domain of magnetic ordering. The critical field of the reorientation transition to an induced easy-plane state in a magnetic field along the trigonal axis has been found to increase compared to that in the unsubstituted crystal.

Magnetic Properties of PrхY1-xFe3(BO3)4

The magnetic properties of trigonal PrxY1-xFe3(BO3)4 compound have been investigated. Anomalies on the magnetization curves induced by a magnetic field are observed for each composition. The calculations were performed using a molecular-field approximation and a crystal-field model for the rare-earth subsystem. Extensive experimental data on the magnetic properties of PrxY1-xFe3(BO3)4 have been interpreted and good agreement between theory and experiment has been achieved.

Role of Magnetic Subsystems to Form a Complex Magnetic Structure Mn2GeO4 Single Crystals

Present paper reports of resonance properties of Mn2GeO4 single crystals. The data confirm the formation of a complex spiral magnetic structure at low temperatures. It is shown that the spin reorientation may be associated with the competition anisotropic contributions of the various subsystems of the manganese ions.

Magnetic Resonance in CuCr2S4 Nanoclusters and Nanocrystals

Nanoclusters and nanocrystals of the room temperature magnetic spinel CuCr2S4 synthesized using a facile solution-based method were examined by magnetic resonance in a wide frequency range 9.6÷80 GHz and at temperatures down to 4.2 K. Decreasing of the resonance field and broadening of the resonance lines are found below ∼ 50 K for both the nanocluster and nanocube samples due to the freezing of magnetic moments of nanocubes and nanocrystalline particles constituting nanoclusters. Additional blocking temperature Tb≅300 K appears in nanoclusters due to the freezing of the magnetic moment of the entire cluster as a whole. Below this temperature, an additional low-field resonance line is found in the resonance spectra of nanoclusters at X-band.