Magnetic properties of a Tb3Ni single crystal

Magnetization measurements, performed on a single crystal of the orthorhombic compound Tb₃Ni, are presented. In this compound, nickel is not magnetic. Below the ordering temperature (62K) the magnetization vs. applied field variations along the three symmetry axes exhibit one or two transitions. These transitions correspond to metamagnetic processes associated with a complex antiferromagnetic structure which is confirmed from neutron diffraction experiments. The analysis of the bulk magnetization results leads to moment directions of terbium atoms which differ from one site to the other. These directions are due to the effect of the strong crystalline electric field which has a very low symmetry. The huge resulting magnetocrystalline anisotropy is also responsible for the large hysteresis loops associated with the metamagnetic transitions at low temperature.     

Thermoreflectance of single crystal Gd

Thermoreflectance spectra for E∥c and E⊥c were measured on a Gd single crystal. The thermoconductance spectra, Δσ_∥ and Δσ_t], are very anisotropic. The strong interband edge at about 0.5 eV is shown to arise from a transition to or from the Fermi level for E⊥c. For E∥c additional effects occur.     

Magnetic and electrical properties of EuPdGe3

We report on the formation and the low-temperature physical properties of a novel compound EuPdGe₃ that crystallizes with the tetragonal BaNiSn₃-type crystal structure. The material exhibits antiferromagnetic ordering below T_N=12.4 K, as inferred from the magnetic susceptibility, heat capacity and electrical resistivity data. The compound shows good metallic conductivity.     

Magnetic and electrical properties of UIrSi3

Magnetic and electrical properties of UIrSi₃ are described. This silicide, which is the only one of UTSi₃ composition (T = transition metal), crystallizes with the BaNiSn₃-type structure and orders antiferromagnetically below 42 K. Metamagnetic transitions are observed for fields of ≈ 5.6 and ≈ 3.2 T at 30 and 38 K, respectively.     

Magnetic properties of CeB6 single crystal

Magnetic measurements of CeB₆ have been made in fields up to 80 kOe at temperatures up to 1000 K. Below 2.3 K, each magnetization vs field curve shows several critical points depending on the direction of field, but between 2.3 and 3 K, the curve is smooth. Above about 3 K, the magnetization curve has a break point at a certain field which increases monotonically with increasing temperature. The paramagnetic susceptibility has been analysed by assuming appropriate values of crystal-field splitting and exchange interactions. From these results, a magnetic phase diagram for CeB₆ has been proposed.     

Magnetic phase transitions in Nd7Rh3 single crystal

Magnetic phase transitions in rare earth intermetallic compound Nd₇Rh₃ have been investigated using a single crystal. Measurement results of magnetization, magnetic susceptibility, specific heat, and electrical resistivity reveal that Nd₇Rh₃ has two magnetic phase transitions at T_N=34 K, T_t2=9.1 K and a change of the magnetic feature at T_t1=6.8 K in the absence of an external magnetic field. Antiferromagnetic orderings exist in all the three magnetic states; a large magnetic anisotropy between the c-axis and the c-plane is observed. In the magnetic phase below T_t2, an irreversible field-induced magnetic phase transition takes place in the c-plane; after removing external magnetic field, a coexistence state of ferro- and antiferromagnetic ordering or a ferrimagnetic state having a remanent magnetization M_R is stabilized. The M_R decays to a certain value for several hours after the first process; a magnetic field cooling effect was also observed in the c-plane below T_t2. In the antiferromagentic state above T_t2, the irreversibility disappears and an ordinary antiferromagnetic state takes place. As the origin of this phenomenon, a kind of martensitic structural transition that is observed in Gd₅Ge₄ can be considered.     

Magnetism in a UNi2/3Rh1/3Al single crystal

We report a magnetization, magnetostriction, electrical resistivity, specific heat and neutron scattering study of a UNi_2/3Rh_1/3Al single crystal, a solid solution of an antiferromagnet UNiAl and a ferromagnet URhAl. The huge uniaxial magnetic anisotropy confining the principal magnetic response to the c axis in the parent compounds persists also for the solid solution. The magnetization curve at 1.6 K has a pronounced S shape with an inflection at 12 T. The temperature dependence of magnetic susceptibility exhibits a maximum around 10 K and is magnetic history dependent at lower temperatures where the resistivity increases linearly with decreasing temperature. The low-temperature ρ(T) anomaly is removed in a magnetic field applied along c, which yields a large negative magnetoresistance amounting to m46 zin 14T (at 2 K). The C/T values exhibit a minimum around 12 K and below 8 K they become nearly constant (about 250 mJ mol^?1 K^?2), which is strongly affected by magnetic fields. Neutron scattering data confirm a non-magnetic ground state of UNi_2/3Rh_1/3Al. The bulk properties at low temperatures are tentatively attributed to the freezing of U magnetic moments with antiferromagnetic correlations. The additional intensities detected on top of nuclear reflections in neutron diffraction in a magnetic field applied along c are found to be proportional to the field-induced magnetization, which reflects field-induced ferromagnetic coupling of U magnetic moments. This scenario is corroborated also by finding low-temperature magnetostriction data that also scale with the square of magnetization.     

Magnetic properties of A DyNi2 single crystal

Magnetic measurements have been performed on a single crystal of DyNi₂ in applied fields up to 135 kOe. In the ferromagnetic range (T_c = 25 K), the easy magnetization direction is [100] and the hardest one is [111]. Crystal field parameters have been determined from the field and temperature dependence of the magnetization measured along the three principal axes. A two-dimensional model has been used to take into account the rotation of magnetization towards the field. The deduced parameters are W = -0.8 K and x = 0.49. The corresponding anisotropy is very large: especially even a field of 135 kOe applied along a difficult magnetization axis cannot rotate the magnetization along this direction.     

EPR study of Gd3+ in a ferroelastic BiVO4 single crystal

Electron paramagnetic resonance of the Gd³⁺ ion in a ferroelastic BiVO₄ single crystal with a single domain, grown by the Czochralski method, has been investigated at room temperature using a Q-band spectrometer. The rotation patterns of the resonance fields measured in the crystallographic planes are analyzed using a monoclinic spin Hamiltonian. The principal Z-axis of the second-order zero-field splitting tensorD is found to be along the crystallographicb-axis. Spin Hamiltonian parameters together with the principal axes ofg andD tensors in the monoclinic plane show that the local site symmetry of Gd³⁺ ion in BiVO₄ crystal is monoclinic and that the Gd³⁺ ion substitutes for Bi³⁺ ion.     

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.     

Magnetic characteristics of PrCd single crystal

Magnetic measurements have been made along the [100], [110] and [111]-axes of PrCd single crystal in magnetic fields up to 70 kOe in the temperature range from 4.2 to 300 K. PrCd shows metamagnetism below T_t = 25 K in which two critical fields are observed in the magnetization processes along the [110] and [111]-axes and a critical field along the [100]-axis. The metamagnetic behaviour is interpreted by a noncollinear antiferromagnetic model with the Pr moments of ～ 2μ_B directed to the 〈111〉-axes.     

EPR of Gd3+ - doped CeF3 single crystal: Linewidth variation with temperature

Detailed X-band EPR study of a Gd³⁺-doped CeF₃ single crystal has been made from 4.2 to 473 K, with particular attention to EPR linewidths. In general, it is found that there are four regions over which the log-log plot of the linewidth versus temperature is linear, implying separate power-law dependences of the linewidth. Gd³⁺ spin Hamiltonian parameters in CeF₃ have been estimated at various temperatures from the line positions. From the linewidth variation with temperature the Debye temperature has determined to be about 140 K.     

Magnetic and electrical properties of cobalt oxyborate Co3BO5

Single crystals of cobalt oxyborate Co₃BO₅ are synthesized. The results of investigations into the structural, magnetic, and electrical properties are reported. It is found that Co₃BO₅ crystals exhibit two magnetic anomalies at T ₁ = 17 K and T ₂ = 45 K. The temperature dependence of the electrical resistivity is investigated. Deviations both from the activation law of variation in the electrical resistance and from the Mott variable-range hopping conduction are revealed.     

Room temperature ferroelectricity of tetragonally strained SrTiO3 thin films on single crystal Rh substrates

Epitaxial SrTiO₃ thin films were deposited on single crystalline Rh substrates by pulsed laser deposition. The tetragonally stained structure of the SrTiO₃ thin films with a c/a ratio of 1.04 was confirmed by x-ray diffraction experiments. The SrTiO₃ thin films exhibited good ferroelectric properties with a high remanent polarization (2P_r) of 8 μC/cm² and a canonical ferroelectric piezoresponse hysteresis loop at room temperature. We estimated a high activation electric field of about 6.4 MV/cm for domain wall creeping. This activation electric field is higher than that of typical ferroelectric materials such as PbTiO₃.     

Transport properties of single crystal

Transport properties of BaNi₂P₂ single crystals prepared by high-pressure synthesis method have been investigated. The temperature dependence of the resistivity is that of a typical metal with the anisotropy ratio ρ/ρ of 6.3 and suggests that electron–phonon interaction dominates the scattering mechanism. We have also found that the Hall effect and the magnetoresistance can be explained by a two-carrier model which is consistent with a multiple-band structure with both hole and electron characters.     

Magnetic phase in the near-surface region of an FeBO3 single crystal

An FeBO3 single crystal was studied from 291 K up to the Neel temperature T(N) = 348.35 K by depth selective conversion electron Mossbauer spectroscopy in ultrahigh vacuum (10(-9) mbar). A new magnetic near-surface phase was found. Its thickness D diverges on approaching T(N) and gives a critical exponent for the correlation length of nu = 0.59(4). The phase boundary between the bulk and near-surface phase could be identified.     

NMR investigation of defect properties in single crystal SrTiO3

Abstract

⁴⁹Ti and ⁸⁷Sr nuclear magnetic resonance measurements were performed in single crystalline SrTiO₃ between 90 K and 1800 K at various oxygen partical pressures. The NMR lines are found to be shifted with rising temperature due to oxygen vacancies acting as donors. Furthermore, three distinct motion-induced nuclear spin relaxation rates could be observed. The corresponding jump rates are attributed to the following processes: translational jumps of charged oxygen vacancies between oxygen sites, localized motion of oxygen vacancies in Fe-vacancy complexes, self diffusion of Sr²⁺.