S.B. Zhang

Large magnetic entropy change near room temperature in antiperovskite SnCMn3

We report the observation of large magnetocaloric effect near room temperature in antipervoskite SnCMn3. The maximal magnetic entropy change at the first-order ferrimagnetic-paramagnetic transition temperature (TC 279 K) is about 80.69mJ/cm3 K and 133mJ/cm3 K under the magnetic field of 20 kOe and 48 kOe, respectively. These values are close to those of typical magnetocaloric materials. The large magnetocaloric effect is associated with the sharp change of lattice, resistivity and magnetization in the vicinity of TC. Through the measurements of Seebeck coefficient and normal Hall effect, the title system is found to undergo a reconstruction of electronic structure at TC. Considering its low-cost and innocuous raw materials, Mn-based antiperovskite compounds are suggested to be appropriate for pursuing new materials with larger magnetocaloric effect.

Crystal growth and superconductivity of FeSex

In this work, crystals of FeSex have been grown by a flux approach. The crystallization process is divided into two stages. First, stoichiometric polycrystal FeSe0.82 was sintered in a solid state reaction. Then, FeSex crystals with a size about 500 µm were successfully grown in an evacuated sealed quartz tube using a NaCl/KCl flux. The products include two crystal structures: tetragonal and hexagonal. The electronic transport and magnetic property measurements show that FeSex crystals exhibit a superconducting transition at about 10 K.

Ferromagnetism in Cr substituted SrMoO3 system

Systematic studies of structural, magnetic, electric transport, and specific heat properties have been performed on lightly Cr-doped molybdates SrMo1−xCrxO3 (0⩽x⩽0.10). Based on the analysis of structural parameter variations, the valence state of the doped Cr ions in SrMo1−xCrxO3 system is suggested to be +2. Cr substitution as low as x=0.025 is sufficient to drive SrMo1−xCrxO3 system from the Pauli-paramagnetic state to a ferromagnetic state. The Curie temperature TC increases monotonically with increasing Cr-doping content. All samples exhibit metalliclike transport behavior in the whole studied temperature range except for the x=0.10 sample. The magnitude of the resistivity increases monotonically with increasing Cr-doping level. The evolution of the magnetic and resistive properties with Cr-doping content x may be related to the narrowed d-band width due to Cr substitution. In addition, the temperature dependence of specific heat for all samples has also been studied.

Growth and optical properties of transparent CaMoO4 films by chemical solution deposition on Si and glass substrates

Nanocrystalline CaMoO4 (CMO) thin films were fabricated on Si and glass substrates via the chemical solution deposition (CSD) method. From x-ray diffraction, atomic force microscopy and Fourier transform infrared spectra results, relatively smooth Scheelite-type CMO thin films can be fabricated within the annealing temperature range from 400 to 700??C. The band gap is 4.18?eV calculated from the optical transmission spectra and the photoluminescence (PL) emission spectra show that the CMO thin films on Si have a broad green emission band centred at 490?nm. Our experimental results show that the CSD method is an alternative method to prepare nanocrystalline CMO thin films with a great PL property at low annealing temperatures.

Superconductivity and single crystal growth of Ni0.05TaS2

Abstract Superconductivity was discovered in a Ni0.05TaS2 single crystal. A Ni0.05TaS2 single crystal was successfully grown via the NaCl/KCl flux method. The obtained lattice constant c of Ni0.05TaS2 is 1.1999 nm, which is significantly smaller than that of 2H–TaS2 (1.208 nm). Electrical resistivity and magnetization measurements reveal that the superconductivity transition temperature of Ni0.05TaS2 is enhanced from 0.8 K (2H–TaS2) to 3.9 K. The charge-density-wave transition of the matrix compound 2H–TaS2 is suppressed in Ni0.05TaS2. The success of Ni0.05TaS2 single crystal growth via a NaCl/KCl flux demonstrates that NaCl/KCl flux method will be a feasible method for single crystal growth of the layered transition metal dichalcogenides.

Mn doping-induced semiconducting behavior in the perovskite molybdates SrMo1−xMnxO3(0≤x≤0.20)

The effect of Mn doping on structural, magnetic, electronic transport, and specific heat properties in 4d perovskites SrMo1−xMnxO3(0≤x≤0.20) has been investigated. The Mn doping at the Mo site does not change the space group of the samples, but increases the structural parameter a monotonically. All Mn-doped samples show Curie-Weiss paramagnetic behaviors due to the appearance of localized moment, and the magnetic susceptibility χ increases with increasing the Mn-doping content. Samples (x≥0.03) exhibit semiconducting transport behavior, while x=0.01 shows a metallic behavior with an upturn below T1. The magnitude of resistivity monotonically increases with increasing Mn-doping content. The evolution of the resistive properties is discussed according to the competition among Kondo scattering, electron-electron interaction, and the disorder effect. In addition, the electron-electron interaction intensity increases with the increasing of Mn-doping content according to the study of specific heat properties.

Magnetic and Transport Properties Based on Transition-Metal Compounds

1 Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China 2 Frontier Research Center, Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan 3 Advanced Solid State Chemistry Laboratory, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan 4 Laboratory for Pohang Emergent Materials, Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea