Effect of Gd-Mn exchange on phase transitions in GdMn<Subscript>2</Subscript>O<Subscript>5</Subscript> induced by a strong magnetic field

Complex studies of the magnetic, magnetoelectric, and magnetoelastic properties of GdMn₂O₅ single crystals in strong pulsed magnetic fields are carried out in order to obtain additional indirect information on the character of the rare-earth and manganese spin ordering. It is shown that magnetic ordering of Gd³⁺ spins affects the manganese sublattice spin orientation and initiates new magnetic phase transitions. The observed magnetoelectric properties of the GdMn₂O₅ system are interpreted in terms of the theory of phase transitions.     

Biologically Active Coordination Compounds of Germanium. Synthesis and Physicochemical Properties

Russian Journal of Organic Chemistry - A promising area of modern coordination and supramolecular chemistry is the synthesis of biologically active compounds of germanium and creation of effective...     

Anomalies in the magnetic and magnetoelastic properties of Sm<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Sr<Subscript>x</Subscript>MnO<Subscript>3</Subscript> single crystals (<Emphasis Type="Italic">x</Emphasis> ∼ 0.5) at phase transitions

By studying the magnetic and magnetoelastic properties, it is established that, as the temperature is lowered, Sm_1?xSr_xMnO₃ single crystals (x=0.5, 0.55) undergo spontaneous phase transitions from the paramagnetic to a local charge-ordered state at T_co=220 K and to an A-type antiferromagnetic state at T_N=175 K. It is shown that strong magnetic fields (H_cr ～ 200 kOe) break up the antiferromagnetic order and charge ordering and drive a phase transition to a conducting ferromagnetic state. H-T phase diagrams are constructed for single crystals with x=0.5 and 0.55.     

Colossal magnetodielectric effect in SmFe<Subscript>3</Subscript>(BO<Subscript>3</Subscript>)<Subscript>4</Subscript> multiferroic

The colossal (more than threefold) decrease in the dielectric constant ɛ in the easy-plane SmFe₃(BO₃)₄ ferroborate in a magnetic field of ∼5 kOe applied in the basal ab plane of the crystal has been found. A close relation of this effect to anomalies in the field dependence of the electric polarization has been established. It has been shown that this magnetodielectric effect is due to the contribution to ɛ from the electric susceptibility, which is related to the rotation of spins in the ab plane, arises in the region of the antiferromagnetic ordering T < T _N = 33 K, and is suppressed by the magnetic field. A theoretical model describing the main features of the behavior of ɛ and electric polarization in the magnetic field has been proposed, taking into account the additional anisotropy in the basal plane induced by the magnetoelastic stresses.     

Magnetoelectric interactions in rare-earth ferroborates

Magnetic-field-induced phase transitions in single crystals of the rare-earth ferroborates GdFe₃(BO₃)₄ and NdFe₃(BO₃)₄ have been studied by measuring magnetoelectric dependences and torque curves. These phase transitions can serve as one of the possible mechanisms for magnetic control of electric polarization. Magnetic phase transitions in GdFe₃(BO₃)₄ are analyzed theoretically.     

The nature of magnetoelastic anomalies in Nd<Subscript>0.5</Subscript>Sr<Subscript>0.5</Subscript>MnO<Subscript>3</Subscript> upon suppression of charge ordering by a magnetic field

This paper reports on the results of investigations into the magnetic and magnetoelastic properties of Nd_0.5Sr_0.5MnO₃ single crystals in pulsed magnetic fields up to 250 kOe, the magnetic and kinetic properties of these crystals in weak static magnetic fields, and their thermal expansion. It is demonstrated that the studied properties exhibit a number of anomalies due to a transition from the antiferromagnetic semiconducting state to the ferromagnetic metallic state upon suppression of charge ordering.     

Magnetic properties of TmxDy1−xFeO3 single crystals

The magnetic behaviour of Tm_xDy_1?xFeO₃ (x = 0.3; 0.5; 0.7; 1.0) single crystals in the temperature range 90-4.2° K were investigated. The transition from the weak ferromagnetic to antiferromagnetic state was observed at about 9° K for Tm_0.3Dy_0.7FeO₃ single crystal. The reorientation of weak ferromagnetic moment from c- to a-axis was observed for Tm_0.7Dy_0.3FeO₃ single crystal at 35–65° K. The magnetic structure change of iron and rare-earth ions took place when external magnetic field was applied. The thulium and disprosium ion interaction does not essentially influence on the single crystal magnetic properties of the substituted compounds in a low temperature range.     

Effect of the Cationic Moiety on the Antimicrobial Activity of Sterically Hindered Isatin 3-Hydrazone Derivatives

Russian Journal of Organic Chemistry - Water-soluble 1-(3,5-di-tert-butyl-4-hydroxybenzyl)isatin 3-acylhydrazones containing an acyclic, bicyclic, or pyridinium quaternary ammonium center in the...     

Synthesis of catalyst based on sol microspheres coated with pyrolytic tungsten and study of its influence on production of metallic germanium

Pyrolytic tungsten coatings were deposited onto the surface of sol microspheres with tungsten hexacarbonyl used as precursor. A method was developed for reduction of germanium tetrachloride in the presence of a catalyst based on sol microspheres coated with pyrolytic tungsten. The method makes it possible to reduce the process temperature and diminish the number of stages in production of germanium. The kinetic characteristics of the catalytic reduction of germanium tetrachloride with hydrogen were determined.     

Magnetic,dielectric and magnetoelectric properties of new family of orthorhombic multiferroic Eu1−xYxMNO3 manganites

Multiferroic ground states with a spatially modulated antiferromagnetic structure and electric polarization have been revealed in Eu_1−xY_xMnO₃ (0.2?x?0.5$0.2?x?0.5$) single crystals. While the slightly substituted (x?0.1$x?0.1$) compounds exhibited a transition from the incommensurate (IC) to the canted antiferromagnetic (CAF) state at _TCA<_TN$T_{\mathrm{CA}}<T_{\mathrm{N}}$, the transitions from IC to commensurate ferroelectric (C/FE) phase were observed at _Tlock<_TN$T_{\mathrm{lock}}<T_{\mathrm{N}}$ for x>0.2$x>0.2$. Various phase transitions were observed in the magnetic fields up to 250 kOe along a, b, c axes by magnetization, magnetostriction and electric polarization measurements which show an existence of a spontaneous electric polarization below T_lock.