[en] Neutron scattering experiments have been performed to reveal the magnetic excitation in ferromagnet CeAgSb₂. Crystalline electric field excitations were observed at 5.2 and 12.5 meV in the paramagnetic state. Our analysis concluded that | ±((1)/(2))> is the ground state. The observed ferromagnetic moment is in good agreement with the ground-state saturation moment, g_Jμ_BJ_z∼0.43 μ_B. The spontaneous moment along the c-axis decreases with increasing the field perpendicular to the c-axis, and disappear at the critical field H_c, where the magnetization curve shows the kink behavior

[en] Highlights: • Y₃Ru₄Ge₁₃ is a low carrier density (10²⁰/cm³) semimetal and exhibits bulk superconductivity. • The superconductivity arises due to inter-valley electron-phonon interactions. • Hall coefficient has unusual temperature dependence similar to both High-Tc and layered compounds like MgB₂. • These classes of materials have good thermoelectric properties. • We need good data on single crystals for further understanding of thermoelectric properties. -- Abstract: We have successfully grown the single crystal of a low carrier density system Y₃Ru₄Ge₁₃ which crystallises in the cubic crystal structure with the space group Pm3n. Y₃Ru₄Ge₁₃ exhibits superconductivity below 2.85 K as determined from the electrical resistivity, magnetic susceptibility and heat capacity measurements. The bulk measurements indicate multi-band superconductivity in this low carrier system. Hall effect measurements show that the Hall coefficient R_H is positive and it decreases rapidly with temperature which is highly unusual. The simple estimation of the carrier concentration gives a value (10²⁰/cm³) which is 2–3 orders of magnitude lower than that of a conventional metal like Cu which seems to suggest that Y₃Ru₄Ge₁₃ is a semimetal that display multiband superconductivity

[en] The localized 4f electrons in the rare-earth based intermetallic compounds exhibit interesting magnetic properties. In particular, the Ce-based compounds are the most extensively studied owing to the close proximity of the 4f level to the Fermi energy. The interesting magnetic properties, like heavy fermion behavior, long range magnetic order, valence fluctuations etc., occur due to the competition between the indirect exchange interaction mediated by the conduction electrons, the so called Ruderman, Kittel, Kasuya and Yosida (RKKY) interaction and the Kondo effect. The RKKY interaction favours magnetic ordering while the Kondo effect quenches the localized magnetic moments. This competition is well documented in literature by the Doniach model. Most of the cerium based intermetallic compounds order antiferromagnetically because RKKY interaction overcomes the Kondo effect at low temperature. The magnetic ordering can be tuned by means of non-thermal external control parameters such as pressure, magnetic field and composition leading to a paramagnetic state. The point at which the magnetically ordered state transforms itself to a non-magnetic state is called the quantum critical point. Presented in this talk is the crystal growth, anisotropic physical properties and the quantum critical behavior in some of the cerium compounds

[en] The growth kinetics of YBCO single crystal from high temperature solution of YBCO-BaO/CuO solute-solvent system has been studied. Based on regular solution model and classical nucleation theory the thermodynamical data investigated for the system are used to determine the nucleation parameters: interfacial energy, metastable zone-width (supercooling temperature), free energy change, critical nucleation radius etc, which leads to the understanding of the nucleation phenomena of YBCO. (orig.)

[en] Employing the time differential perturbed angular distribution (TDPAD) method we have studied the temperature dependence of the magnetic hyperfine field, B_hf for ⁶⁶Ga in 122 type pnictides, XFe₂As₂ (X = Ca and Sr). The saturation hyperfine field, B_hf (0) of Ga in Ca(Sr)Fe₂As₂ have been observed to be 16.2 kG and 22 kG respectively. Scaled by the hyperfine field of ⁶⁶Ga in ferromagnetic elements Fe, Co and Ni, our B_hf (0) data indicate small local moments on Fe, consistent with itinerant type magnetism of these materials. The observed temperature dependence of the hyperfine field data suggests second order type magnetic phase transition with a critical exponent β≈0.22(3) indicating quasi-two dimensional magnetic ordering, possibly due to canting of Fe moments out of the ab plane. - Highlights: • We provide detailed measurement of ⁶⁶Ga hyperfine field in XFe₂As₂ (X = Ca, Sr) employing TDPAD technique. • Hyperfine field data shows second order type magnetic transition. • The critical exponent near phase transition suggests moments are out of ab plane. • Fe possesses small local moment showing itinerant behaviour

[en] Single crystals of Zr added YBa₂Cu₃O_7-δ were grown using excess BaO-CuO as flux for Zr concentration 0.1, 0.2 and 0.3%. The growth mechanism was found to vary for pure and Zr added single crystals. The optical micrograph of the grown crystals reveals that the spiral growth mechanism is observed in the case of pure YBCO single crystals. A possible explanation for the shape and formation of the spirals has been given by the Periodic Bond Chain (PBC) theory. The Zr addition greatly affects the spiral growth patterns and the growth is facilitated by layer growth mechanism and hence, slightly thicker crystals have been obtained. The susceptibility measurement showed a sharp transition at 71K for Zr 0.1wt% added single crystals, without any further oxygen treatment. (author)

[en] We have succeeded in growing single crystals of the cerium-transition metal intermetallics CeTSb₂ (T: Cu, Au, Ni) with the tetragonal structure via the self-flux method, and measured the electrical resistivity, magnetic susceptibility, magnetization and specific heat. CeCuSb₂ and CeAuSb₂ are antiferromagnets with Neel temperatures of 6.9 and 5.0 K, respectively. CeCuSb₂ is a heavy-fermion antiferromagnet with an electronic specific heat coefficient γ=200 mJ/K² mol. CeAuSb₂ also is a similar compound with an antiferromagnetic easy axis along the [0 0 1] direction. CeNiSb₂ is a ferromagnet with a Curie temperature of 6.0 K. The easy axis is oriented along [1 0 0], with a moment of 0.6μ_B/Ce

[en] The magnetization of ErCu₂ has been measured in high magnetic fields up to 45 T. Metamagnetic transitions are found at 16.5, 0.7 and 13 T for the field applied along the a-, b- and c-axis, respectively. The sharp metamagnetic transition for H parallel b is due to the antiferromagnetic ordering, while the other two metamagnetic transitions originate from the crossover of the crystalline-electric-field energy levels of the 4f electrons

[en] We report anisotropic dc magnetic susceptibility χ(T), isothermal magnetization M(H), electrical resistivity ρ(T) and heat capacity C(T) measurements on a high quality single crystalline sample of NdCrSb₃. The crystal exhibits ferromagnetic ordering below T_C = 100 K due to ordering of Cr spins. The ferromagnetic phase is highly anisotropic. The anisotropy becomes even more evident at low temperatures where the rare earth ion (Nd³⁺) gets magnetically ordered. Nd moments order ferromagnetically below 10 K. The magnetic interplay between these two species (Cr³⁺ and Nd³⁺ ions) gives NdCrSb₃ a complex magnetic phase diagram

[en] Single crystals of pure and transition metal doped CaFe_2-xT_xAs₂ (T = Co and Ni) have been grown by flux method using molten Sn as solvent. The magnetic and superconducting properties of the grown crystals were studied by measuring the electrical resistivity, magnetic susceptibility and neutron diffraction measurements. A spin density wave (SDW)/structural transition is observed at 170 K for the pure CaFe₂As₂ single crystal and it gets suppressed with T (Co and Ni) doping. For an optimum dopant concentration of x = 0.06, the sample becomes superconducting. From the detailed studies on CaFe_2-xNi_xAs₂ single crystals we have constructed a magnetic phase diagram. (author)