Magnetic properties of UFe5Sn single crystals

Millimetre-size UFe₅Sn single crystals were grown by the top seed solution growth method and characterized by magnetization, ⁵⁷Fe Mössbauer spectroscopy and specific heat measurements in order to study the magnetic transitions detected in powder samples at 248 and 178 K. The magnetization measurements show different behaviour along the three crystallographic directions but with similar values of spontaneous magnetization along a and c. The transition at 248 K is associated with ferromagnetic ordering of iron moments along the c-axis, while the transition at lower temperature is associated with a reorientation towards b. Mössbauer data show that this reorientation is concomitant to the ordering of the Fe2 sites, which in a large proportion remain paramagnetic between the two transition temperatures. Specific heat measurements are consistent with the establishment of magnetic ordering at 248 K, followed by a spin reorientation at 178 K, yielding γ(0 K)140 mJ/(mol K²) and θ290 K for UFe₅Sn.     

Magnetic properties of oxides and silicon single crystals

The magnetic properties of single crystals Si, SrTiO₃, LaAlO₃, MgO, and (La,Sr)(Al,Ta)O₃ were investigated systematically. Three origins of the magnetizations of these crystals, namely, an intrinsic diamagnetic, a paramagnetic, and a ferromagnetic contribution, have been found to influence the magnetic signals measured on the crystals, in some important application scenarios such crystals being served as substrates with the magnetic thin film epitaxially grown on. Quantitative analyses methodologies were developed and thorough investigations were performed on the crystals with the intrinsic materials parameters thus revealed, especially that the intrinsic diamagnetic susceptibility differential dχ_dia/dT were identified quantitatively for the first time in SrTiO₃, LaAlO₃, MgO, and (La,Sr)(Al,Ta)O₃. The paramagnetic contribution is found to be the key in terms of the magnetic properties of the crystals, which in turn is in fact a consequence of the 3d impurities doping inside the crystal. All the intrinsic materials parameters are given in this paper as datasets, the datasets are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00028.     

Magnetic and magnetoelastic properties of GdZn single crystals

The magnetic and magnetoelastic properties of GdZn have been investigated by various ways: magnetization, magnetic susceptibility, magnetocaloric effect, pressure dependence of the Curie temperature, spontaneous magnetostriction, parastriction and sound velocity measurements. The γ-mode strain is large for an S-state ion, and two orders of magnitude larger than the ?-one. Both the first-order B^γ,2 and the three isotropic second-order magnetoelastic coefficients exhibit a m²(1 ? 0.5m²) thermal variation (where m(T, H) is the reduced magnetization), which differs from the classical behaviour. All the results suggest a noticeable contribution of the conduction band to the magnetism of GdZn.     

Magnetic properties of V5S8 single crystals

The magnetic properties of V₅S₈ single crystals have been investigated by susceptibility and torque measurements. The susceptibilities parallel and perpendicular to the magnetic easy axis show a remarkable anisotropy below the Neel temperature of 32 K and are nearly Isotropie above that temperature. The easy axis is found to be nearly along the c-axis of the monoclinic lattice, being inclined at an angle of 9.6 ± 1.0° from the c-axis toward the a-axis. The torque curves, measured up to 24.4 kOe at liquid helium temperature, deviate from the usual form of a sine function with increasing magnetic field. The analysis of these torque curves suggests that spin flopping may occur at 43 kOe, a comparatively low critical field. Using these experimental results, a localized d-electron model for a particular site of the vanadium-ion, proposed by previous investigators, is examined.     

Magnetic properties of La2CuO4 single crystals

Magnetic susceptibility x of La₂CuO₄ crystals have been measured with external magnetic field perpendicular to and within the c plane. A kind of ordering or condensation of the spin system with the spin direction parallel to the c axis has been found although it is difficult to consistently explain all of the observed behaviors. Even above the ordering temperature (⋍ 250K), uniaxial anisotropy of x has also been observed.     

Magnetic viscosity in NdFeB and SmCo5 alloys

The magnetic viscosity parameters (kT/q=S_v) of spherical specimens of NdFeB and SmCo₅ have been measured as functions of intensity of magnetization. Two methods of measurement were used for both specimens. For the NdFeB specimen the value of kT/q varies from 50 Oe at M=+400 G to 80 Oe at M=-900 G. For SmCo₅, kT/q varies from approximately 18 to 21 Oe and has a maximum value at M=0. For each specimen the two methods of measurement give results which are in agreement within the limits of experimental error. The volumes of material which are subject to thermal activation, e.g. pinning or nucleation centres, range from 4 to 6.4X10^-19 cm³ for NdFeB and is about 2.4X10^-18 cm³ for SmCo₅.     

Magnetic and transport properties of transition-metal implanted ZnO single crystals

ZnO single crystals were implanted with Mn, Co and Ni with fluences between 1 × 10¹⁶ cm^-2 and 1 × 10¹⁷ cm^-2 and energy of 200 keV. Results indicate that aggregation of transition metal ions in the as implanted state occurs only in the case of Ni. After an annealing stage to recover the ZnO structure aggregation occurs for the higher fluences of all implanted species. For lower concentrations paramagnetic behaviour with magnetic moments close to those of individual ions is observed. No polarised impurity band is formed as a result of the presence of transition metal ions and all samples show electrical conduction by carriers in extended states of ZnO. Significant values of magnetoresistance are measured at low temperatures, where electrical transport is described by hopping mechanisms between localized states. The sign of the magnetoresistance is dependent of the doping ion and is correlated with the observed aggregation.     

Magnetic and transport properties of YbRhIn5 and YbIrIn5 single crystals

Single crystals of YbRhIn₅ and YbIrIn₅ have been grown by flux method. The crystals were characterized by means of X-ray diffraction, magnetic and electrical transport measurements. Both compounds were found to be weak diamagnets with metallic character of the electrical conductivity and the Seebeck coefficient.     

Magnetic and resonance properties of LiCu2O2 single crystals

We study the structural, magnetic, and resonance properties of LiCu₂O₂ single crystals grown by the spontaneous crystallization method. The data are interpreted on the assumption that the crystalline structure of the grown single crystals is orthorhombic. Long-range antiferromagnetic order sets in at temperatures below 22.5 K, while above this temperature the dependence of the magnetic susceptibility has a shape characteristic of interacting antiferromagnetic Heisenberg chains. We hypothesize that long-range magnetic order sets in below 22.5 K through the destruction of the ideal ladder structure of LiCu₂O₂ because of partial redistribution of copper and lithium ions at the crystal lattice sites and because of the presence of other defects in the crystalline structure. Zh. éksp. Teor. Fiz. 113, 1866–1876 (May 1998)     

Magnetic properties and phase transitions in hexagonal DyMnO3 single crystals

DyMnO₃ single crystals of hexagonal modification were grown for the first time by zone melting, and their anisotropic magnetic properties were studied in detail. At T ～ 7 K, a small uncompensated magnetic moment (～1 μ_B per formula unit) is shown to occur along the hexagonal axis. At temperatures 7–45 K, a transition from the purely antiferromagnetic state to a state with uncompensated magnetic moment was revealed; the transition is induced by a magnetic field H parallel to the c axis. This transition seems to be due to a ferrimagnetic ordering of the moments of Dy cations located in nonequivalent crystallographic positions.     

Magnetic and transport properties of UBi2 and USb2 single crystals

The thermoelectric power, S(T), of USb₂ and UBi₂, which are tetragonal, uniaxial antiferromagnets below T _N?=?202?K and 180.8?K, respectively, have been examined between 0.4?K and 300?K. The values of S(T), up to now known above 70?K for USb₂ and unknown for UBi₂, are positive along the a-axis for both compounds in the whole examined temperature range. The S(T) data for the c-axis (the easy magnetization axis) are positive near room temperature for USb₂ and UBi₂ but becomes negative below 120?K and 170?K, respectively, with two very deep minima in S(T) dependence for USb₂. In the latter compound the Fermi surface, known from literature, is composed of the only cylindrical sheets that are slightly corrugated and parallel to the c-axis. UBi₂, the Fermi surface of which is composed of one spherical and two cylindrical sheets, shows corresponding minima although less pronounced than those in USb₂. Having at disposal the highest purity single crystals in comparison to those for which the resistivity, ρ(T), has been reported in literature, the ρ(T) anisotropy was re-examined for these two systems. Magnon and phonon contributions to their total electrical resistivity have been determined and the critical fluctuation behaviour of the resistivity near T _N for both dipnictides has been analysed. Although the magnetic susceptibilities of UBi₂ and USb₂ reveal a similarity, their transport properties are significantly different due to the difference in the Fermi surface topology.     

离子注入金红石单晶生成的金属Ni纳米晶的磁学性能研究

研究了能量为64keV、注量1×1017cm-2的Ni离子注入金红石TiO2单晶制备的植入金属纳米晶的微观结构和磁学性能。注入层的结构和磁学性能采用透射电子显微分析（TEM）和超导量子干涉磁强计（SQUID）进行分析。结果表明,金红石单晶中有尺寸为3～18nm的金属Ni纳米晶生成,注入区域基体明显非晶化。10K温度下金属Ni纳米晶的矫顽力约为16.8kA·m-1,比Ni块材的矫顽力大。样品的零场冷却/有场冷却（ZFC/FC）曲线表明,金属Ni纳米晶的截止温度约为85K。     

离子注入金红石单晶生成的金属Ni纳米晶的磁学性能研究

 研究了能量为64keV、注量1×10¹⁷cm^-2的Ni离子注入金红石TiO₂单晶制备的植入金属纳米晶的微观结构和磁学性能。注入层的结构和磁学性能采用透射电子显微分析（TEM）和超导量子干涉磁强计（SQUID）进行分析。结果表明，金红石单晶中有尺寸为3～18nm的金属Ni纳米晶生成，注入区域基体明显非晶化。10K温度下金属Ni纳米晶的矫顽力约为16.8kA·m^-1，比Ni块材的矫顽力大。样品的零场冷却/有场冷却（ZFC/FC）曲线表明，金属Ni纳米晶的截止温度约为85K。     

Electrical and optical properties of CuIn5S8 single crystals

Summary Several transport and optical properties have been studied onn-type CuIn₅S₈ single crystals. The energy gap at 0 K was determined from the electrical measurements to be 1.4 eV. An anisotropy of the magnetoresistance effect was found and it was suggested that the minima of the conduction band were located at points along the [100] directions ink-space. An optical-absorption band was found in an infrared region of (1÷1.6) μm and was attributed to the transitions from the lowest conduction band situated along the [100] directions to an upper conduction band. Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16, 1982.     

Magnetic control of magnetic shape-memory single crystals

We present a phenomenological model for the magneto-mechanical evolution of shape-memory alloy single crystals. The existence of solutions for given magnetic field is commented and optimal control results are established.     

Magnetic inhomogeneity of lanthanum manganites single crystals

The magnetic inhomogeneity of the single crystals of La_1−xD_xMnO₃, where D=Ca, Sr, Ba, is studied. The Curie temperature distribution function is found. The form of this function is shown to depend on whether the mean value of the divalent element concentration is close to the “optimal” concentration (≈1/3) or not. The standard deviation for Curie temperature is evaluated. The correlation between the distribution coefficient for divalent elements and the standard deviation is established.     

Magnetic properties of iron and nickel single crystals magnetized in the trigonal plane

Equations explaining the magnetization curves, the magnetostriction curves, and the galvanomagnetic effect for the trigonal plane of iron and nickel crystals in fields near the saturation magnetization are found from the Akulov theory.Translated from Izvestiya VUZ. Fizika, No. 3, pp. 86–91, March, 1970.