The magnetic structures of HoTiO3 and ErTiO3

The magnetic structures of rare-earth titanium perovskites, ErTiO₃ and HoTiO₃, have been determined at 4.2 K by neutron diffraction. The Er³⁺ moment of (8.5 ± 0.5) μ_B lies along [001] and is colinear with the titanium moment of (-0.7 ± 0.3) μ_B. The Ho³⁺ moment of (8.1 ± 0.5) μ_B is inclined at an angle of 24° to the bc plane and 32° to the ab pla so as to produce an antiferromagnetic ordering of the x component and a ferromagnetic ordering of the y and the z components. The titanium moment of (-0.55 ± 0.3) μ_B lies in the bc plane but its precise direction has not been determined.     

Magnetization and magnetic susceptibility of GdH3

Magnetic susceptibility measurement in the range 1.4 to 4.2 K reveal a maximum in χ at 3.65 K, and two maxima in Δχ/ΔT, one at 3.32 K (assumed to be T_N), and another at 1.8 K. High field magnetization measurements indicate a saturation moment of 7 μ_B.     

Magnetization behaviour of DyAl2 single crystals

We report the theoretical interpretation of the magnetization and the magnetocrystalline anisotropy of ferromagnetic DyAl₂ single crystals between 4.2 and 60 K and magnetic fields up to 15 T. Good agreement between theory and experiment is obtained by using three temperature independent parameters: the two crystal field parameters B₄ = (?0.50 ± 0.05) × 10^?4 meV, B₆ = ? (0.51 ± 0.05) × 10^?6 meV and the Curie temperature T_c = (62 ± 2) K.     

Cs nuclear magnetic resonance study in CsZnCl3 single crystals of perovskite ABX3 type

CsZnCl₃ single crystals were grown by the slow evaporation method, and the spin-lattice relaxation rates and resonance lines of the ¹³³Cs nuclei in the resulting crystals were investigated using FT NMR spectrometry. The temperature dependence of the relaxation rate of the ¹³³Cs nuclei in the CsZnCl₃ crystals was found to be continuous near T_C (=366 K), and was not affected by this phase transition. Our results for CsZnCl₃ are compared with those obtained previously for other CsBCl₃ (B=Mn, Cu, and Cd) perovskite crystals. The Cs relaxation time of CsCdCl₃ is longer than that of CsMnCl₃. The differences between the atomic weights of Mn, Cu, Zn, and Cd are responsible for the differences between the spin-lattice relaxation times of these single crystals. The influence of paramagnetic ions is also important in these crystals. The differences between the spin-lattice relaxation times of these crystals could also be due to differences between the electron structures of their metal ions, in particular the structures of the d electrons.     

Magnetization process and principal magnetic susceptibilities in RbMnF3

The temperature dependence of χ_⊥, initialχ_p (powder), and evaluated χ_∥ for RbMnF₃ are reported for the temperature range of 4.2–106 K. A shallow minimum at $\text{T}\text{T}{}_{\mathrm{N}}\text{? 0.72}$ is observed in χ_⊥. The field dependence of the magnetization shows a smooth rotation of the spins to a normal direction above H_c ? 2.43 kOe at 4.2 K.     

Electroluminescence in LiNbO3 single crystals

The light emission from LiNbO₃ single crystals caused by the applied a.c. high voltage is studied. It is interpreted as electroluminescence due to impact processes of field accelerated electrons. Two bands can be distinguished in the emission spectrum: one larger with the maximum at 660nm and one smaller at about 500nm.     

Magnetic susceptibility and electrical properties of VSe2 single crystals

Magnetic susceptibility, in-plane resistivity and Hall effect data of VSe₂ single-crystal plates are reported. These data exhibit anomalies at ～ 100 K. The occurrence of these anomalies is presumably due to Fermi-surface changes resulting from the onset of a charge density wave instability.     

Electrical and magnetic properties of TmCoIn5 and YbCoIn5 single crystals

Electrical and magnetic properties of TmCoIn₅ and YbCoIn₅ single crystals were investigated by means of electrical resistivity and magnetization measurements in the temperature range from 300 to 0.5 K under the magnetic field up to 5 T. TmCoIn₅ is an antiferromagnetic metal with a Néel temperature T_N=2.6 K. YbCoIn₅ shows non-magnetic behavior, reflecting of divalent Yb ion.     

Anomalies in low-temperature lattice parameters of ErFeO3 and ErAlO3 single crystals: correlation with magnetic properties

The paper presents the results of an experimental study of thermal expansion of isostructural orthorhombic ErFeO₃ and ErAlO₃ single crystals. Changes of lattice parameters have been investigated by X-ray measurements in the 10-300 K temperature range. Above ∼150 K, experimental results correspond well to the phonon mechanism. At low temperatures distinct anisotropic anomalies were observed in both compounds; and a correlation with the magnetic properties of the relevant ions is noted.     

Anisotropic susceptibility of (Ti1−xVx)2O3 single crystals

Anisotropy of the susceptibility, which depends on vanadium concentration, was observed for (Ti_1?xV_x)₂O₃(x=0.005, 0.015, 0.02) single crystals. The anisotropy is hard to interpret by localized magnetic states of vanadium ions.     

Intrinsic magnetic inhomogeneity of Eu substituted La0.7Pb0.3Mno3 single crystals

The study of magnetic and magnetotransport properties of the crystals of (La_1−yEu_y)_0.7Pb_0.3MnO₃ system has been carried out. Eu ions enter the crystals being in trivalent nonmagnetic state. Europium ions possessing of smaller ionic radius in comparison with La ions, induce local distortions of Mn–O–Mn bonds in the system that cause random distribution of magnetic exchange interactions in magnitude and, probably, in sign. The competition of magnetic interactions leads to the appearance of the inhomogeneous magnetic state in the crystals. The enhancement of concentration of Eu ions results in decrease of the Curie temperature and broadening of the inhomogeneous magnetic state area. At y=0–0.4 the coexistence of the paramagnetic phase with conductivity of the polaronic type and the ferromagnetic metallic phase is observed in a bounded temperature interval both above and below T_C. Below T_C the increasing of y up to 0.6 induces the magnetic state representing the coexistence of two different FM phases. These phases are spatially separated due to frustration of FM and AFM exchange interactions on phase boundaries. Above T_C, up to 1.6T_C ferromagnetic clusters exist in a paramagnetic matrix similar to the case of samples with y=0–0.4. Concerning electric properties, the samples with y=0–0.4 reveal the metal–insulator transition at temperature that practically coincides with T_C. The sample with y=0.6 has conductivity of insulator character up to the lowest temperatures. For all investigated compositions y=0–0.6 the CMR effect is observed in the area where the inhomogeneous magnetic state exists. The effect is determined by different conductivity of the coexisting phases, as well as by sensitivity of the inhomogeneous state to external magnetic field.     

Surface characterization of In4Se3 single crystals

Surface properties of indium subselenide (In₄Se₃) were studied. It was confirmed, that the superstructure of this crystal is characterized by nanowire-like cylindrical clusters with diameter dimensions of about 20 nm and stairs along the a-axis up to 5 nm, depending on the cleavage conditions.     

Magnetization studies of TbFeO3

The spontaneous magnetization and principal magnetic susceptibilities of TbFeO₃ were measured from 4.2 to 300 K. The weak ferromagnetic moment is along the c crystallographic axis in the entire temperature range. The field dependence of the magnetization at 4.2 K was also studied. The magnetic behavior is interpreted in terms of an interaction between the ordered Fe³⁺ spin system and the electrons occupying the lowest lying “accidental” doublet of the Tb³⁺ ions. The FeTb interaction and the Tb³⁺ Van Vl eck susceptibility along the c axis play significant roles in determining the magnetic configuration of the Fe³⁺ spin system. No indication was found that the TbTb interaction plays a significant role in the magnetic behavior of TbFeO₃ at temperature above 4.2 K.     

Investigation of phase transition mechanisms of CsH3(SeO3)2 single crystals by observation of nuclear magnetic resonance

The relaxation times of the ¹H and ¹³³Cs nuclei in CsH₃(SeO₃)₂ crystals were investigated using FT NMR. The ¹³³Cs spectrum does change from seven resonance lines to one resonance line near T_m (=350 K). The presence of only one ¹³³Cs signal is due to the liquid state resulting from the melting of the crystal. The variation in the separation of the ¹³³Cs resonance lines with temperature indicates that the EFG at the Cs sites produced by the (SeO₃)²⁻ groups varies with temperature, which in turn means that the atoms neighboring ¹³³Cs are displaced. And, the T₁ for ¹³³Cs is very long and undergoes significant changes near T_m. The change in the temperature dependence of T₁ at T_m for the ¹³³Cs nuclei coincides with the melting temperature. These results are compared with those obtained for MH₃(SeO₃)₂ (M=Na, K, and Cs) crystals.     

Superconducting energy gap in MgCNi3 single crystals

Even though MgCNi₃ contains large molar volume of magnetic Ni atoms it clearly shows superconductivity. The origin of superconductivity in this material has not yet been clarified. There is a lot of discrepancy in experimental results and physical interpretation where even unconventional pairing or a two-band model have been proposed for the system. All that is based on results obtained on polycrystalline samples. Here we present the first point-contact spectroscopy and ac-calorimetry measurements on the MgCNi₃ single crystals of very good quality. Measurements have been performed in the temperature range from 1.5 to 10 K and in magnetic fields up to 8 T. The temperature dependence of the energy gap of the system is presented and compared to the BCS model.     

稀磁半导体Hg0.89Mn0.11Te磁化强度及磁化率的研究

利用MPMS-7(magnetic property measurement system)型超导量子磁强计对垂直布里奇曼法生长的Hg_0.89Mn_0.11Te晶片磁化强度变化规律进行了测量.试验采用了两种不同的外场和冷却条件.首先在5 K恒温下，-5200到5200 kA/m范围内改变磁场强度进行了测定.然后维持800 kA/m恒定磁场，分别在有场冷却和无场冷却条件下，从5到300 K范围内改变温度，研究了变温条件下的磁化特性.并采用分子场近似模型，用类布里渊函数，最小二乘法对磁化强度随磁场强度变化的实验结果进行拟合和分析，结果表明，Mn²⁺离子之间存在反铁磁相互作用.磁化率和温度关系分析表明：在测试范围内Hg_0.89Mn_0.11Te是单一的顺磁相，在高温区磁化率和温度服从居里-万斯定律，呈线性关系，低于40 K时，磁化率和温度的关系偏离居里-万斯定律，表现出顺磁增强现象. 关键词： 0.89Mn_0.11Te')" href="#">Hg_0.89Mn_0.11Te 磁化强度 磁化率 类布里渊函数     

Magnetization and torque measurements on Nd2Fe14B single crystals

Magnetization and torque measurements on single crystal specimens of Nd₂Fe₁₄B have been carried out. The magnetization values measured always in the direction of easy magnetization and those in the [001] direction have been precisely determined at temperatures from 4.2K to 600K with a superconducting magnet up to 52.65 kOe. Below the spin reorientation temperature 135K, the magnetization value of the direction of easy magnetization increases anomalously with decreasing temperature. The direction of easy magnetization tilts from the [001] axis to the [110] axis and this tilt angle has been also precisely determined by torque measurement in the temperature range below the spin reorientation temperature. The four-fold symmetry in torque curve for the (001) plane is continously observed at even up to near room temperature and the [110] direction of easy magnetization and the [100] direction of hard magnetization do not change below and above the spin reorientation temperature.     

Anomalous magnetic behaviour and susceptibility maximum in CeSn3

Anomalous magnetic behaviour observed in one of cerium intermetallic compound, CeSn₃, is analysed in the spirit of the Fermi liquid model, by regarding even the 4f-electrons of cerium as itinerant. It is shown that the appearance of the broad peak of the susceptibility at about 150°K can be attributed to the T²1nT dependence of the susceptibility on temperature.     

Spin glass behaviour and magnetic anisotropy in DyFe4Al8 single crystals

Measurements of electrical resistivity, AC and DC magnetic susceptibilities of a DyFe₄Al₈ single crystal were performed in the temperature range 4.2–300K. A thermomagnetic effect was found below 30K. The strong anisotropy of the magnetic susceptibility occurs in the whole temperature range and is very pronounced at low temperatures. A T²-dependence of the electrical resistivity in the temperature range 4.2–100K and an antiferromagnetic transition at 185K were found. A cusp in the AC susceptibility was observed below 100K with a maximum at 30K.     

Electrical properties of vapour grown ZrSe3 single crystals

Resistivity, Hall coefficient and thermoelectric power measurements of ZrSe₃ single crystals along the chain axis were carried out in the temperature range from 200 to 400 K. Experimental results are explained by the model of compensated semiconductors with two-dimensional characteristics. The activation energy of the donor level is determined to be 0.25 eV and the effective mass of the conduction band parallel to the layer is estimated to be 0.3m₀.