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In this work, the structural, magnetic, thermal, and transport properties of the arc-melted polycrystalline Heusler alloy Co2Ti1.5Sn0.5 are investigated. The alloy crystallizes in an L21 structure with a space group of Fm-3m. The magnetic properties of the alloy depict its antiferromagnetic nature and the alloy exhibits magnetic ordering around Neel Temperature TN = 8.5 K. The effective magnetic moment value obtained from the Curie –Weiss law suggests that the cobalt atom in the alloy is in the low-spin state. From the heat capacity studies, the Sommerfeld coefficient and Debye temperature were determined. In addition, electrical resistivity shows a linear response with increasing temperature, indicating the metallic nature of the alloy.

In this work, the structural, magnetic, thermal, and transport properties of the arc-melted polycrystalline Heusler alloy Co2Ti1.5Sn0.5 are investigated. The alloy crystallizes in an L21 structure with a space group of Fm-3m. The magnetic properties of the alloy depict its antiferromagnetic nature and the alloy exhibits magnetic ordering around Neel Temperature TN = 8.5 K. The effective magnetic moment value obtained from the Curie –Weiss law suggests that the cobalt atom in the alloy is in the low-spin state. From the heat capacity studies, the Sommerfeld coefficient and Debye temperature were determined. In addition, electrical resistivity shows a linear response with increasing temperature, indicating the metallic nature of the alloy. [ABSTRACT FROM AUTHOR]

Organic molecular conductors with a strongly correlated electron system, in which the itinerancy of electrons (or holes) and the electron correlation (U/W, U, the on-site Coulomb repulsion, W, the bandwidth) compete with each other, are promising candidates for achieving superconductivity and also for exploring remarkable physical properties induced by external stimuli such as pressure, light, voltage and current. Our synthetic approach to the construction of strongly correlated organic electron systems is based on chemical modifications to the donor molecule BDH-TTP [2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] capable of producing metallic CT (charge-transfer) salts stable down to low temperatures (4.2–1.5 K). This aims at enhancing the electron correlation in the itinerant electron system by decreasing the bandwidth. Chemical modifications of BDH-TTP such as ring expansion of two outer dithiolane rings, replacement of one sulfur atom in an outer dithiolane ring with an oxygen atom and introduction of two methyl substituents into an outer ditiolane ring led to BDA-TTP [2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene], DHOT-TTP [2-(1,3-dithiolan-2-ylidene)-5-(1,3-oxathiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] and DMDH-TTP [2-(4,5-dimethyl-1,3-dithiolan-2-ylidene)-5-(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene], respectively. In this review, the physical properties and the crystal and electronic structures of molecular conductors derived from these donor molecules will be described.

Abstract Magnetic excitations in the metallic antiferromagnet F e 0.5 M n 0.5 were investigated using the inelastic neutron scattering technique at low temperatures well below the antiferromagnetic transition temperatures (T N). The observed peak positions in low energies well sit on the antiferromagnetic dispersion relation reported in the early study. However, the peak positions in higher energies shift to higher energies than that of the antiferromagnetic spin wave dispersion relation. This behavior is the same as one of the behaviors suggesting that the spin waves merge with the continuum of the individual particle-hole excitations at higher energies in F e 0.7 M n 0.3. [ABSTRACT FROM AUTHOR]

Organic molecular conductors with a strongly correlated electron system, in which the itinerancy of electrons (or holes) and the electron correlation (U/W, U, the on-site Coulomb repulsion, W, the bandwidth) compete with each other, are promising candidates for achieving superconductivity and also for exploring remarkable physical properties induced by external stimuli such as pressure, light, voltage and current. Our synthetic approach to the construction of strongly correlated organic electron systems is based on chemical modifications to the donor molecule BDH-TTP [2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] capable of producing metallic CT (charge-transfer) salts stable down to low temperatures (4.2-1.5 K). This aims at enhancing the electron correlation in the itinerant electron system by decreasing the bandwidth. Chemical modifications of BDH-TTP such as ring expansion of two outer dithiolane rings, replacement of one sulfur atom in an outer dithiolane ring with an oxygen atom and introduction of two methyl substituents into an outer ditiolane ring led to BDA-TTP [2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene], DHOT-TTP [2-(1,3-dithiolan-2-ylidene)-5-(1,3-oxathiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] and DMDH-TTP [2-(4,5-dimethyl-1,3-dithiolan-2-ylidene)-5-(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene], respectively. In this review, the physical properties and the crystal and electronic structures of molecular conductors derived from these donor molecules will be described. [ABSTRACT FROM AUTHOR]

Abstract: Measurements of the electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) on the rare earth ternary intermetallic YMn4Al8 has been performed in the temperature range 10–300K to investigate the electronic structure and the possible existence of pseudogap. YMn4Al8, with linear chains of Mn atoms, is an itinerant electron magnet that has a narrow pseudogap in the spin excitation spectrum. For comparison, the nonmagnetic counterpart YCu4Al8 has also been studied. It is found that the replacement of Cu for Mn leads to a dramatic increase in the electrical conductivity, indicating an increased metallic nature of YCu4Al8. The evident difference in the magnitude of the Seebeck coefficient between YMn4Al8 and YCu4Al8 as well as the sign reversal of S(T) in YCu4Al8 suggest that the Fermi level in YMn4Al8 is located within a rapidly varying density of states (DOS)/pseudogap and a significant change in temperature dependent DOS is taking place. A detailed analysis of the thermal conductivity by separating lattice and electronic contribution and the comparison with the electrical resistivity indicates a more ordered and increased metallic state for YCu4Al8 than that of YMn4Al8. [Copyright &y& Elsevier]

The crystal structure and magnetization of Hf0.8Ta0.2(Fe1−xCox)2 are investigated by X-ray powder diffraction and magnetization measurements. The compounds exhibit the Laves C14 structure for x=0.0–0.2 and the C15 structure for x≥0.3. The structural transition from C14 to C15 leads to an anomaly of the unit cell volume between x=0.2 and 0.3. When x=0.0, the compound undergoes a magnetic phase transition from ferromagnetic to paramagnetic state via the antiferromagnetic state, in which a field-induced metamagnetic transition is observed. When x=0.1 and 0.2, the compounds exhibit unusually small saturation moments, which are considered as antiferromagnetism (with weak ferromagnetic impurities) and weak ferromagnetism or ferrimagnetism, respectively. The formation of the AFM state is associated with a small bond length of Fe atom in the 6h site. When x≥0.3, the compounds exhibit a ferromagnetic to paramagnetic transition, which can be explained by itinerant electron metamagnetism. [Copyright &y& Elsevier]

Abstract: 55Mn-NMR measurements, which revealed previously the presence of spin pseudogap in YMnAl, have been extended to LuMnAl and ScMnAl. Temperature (T) dependences of the Knight shift, K, and the nuclear spin-lattice relaxation rate, , are well explained by the same pseudogap model used to explain a broad maximum observed in the T-dependence of the susceptibility, indicating common nature in the spin excitation spectrum in the quasi-one-dimensional itinerant-electron compounds. [Copyright &y& Elsevier]

Abstract: The ground state of the quasi-one-dimensional itinerant electron magnet with strong electron correlation has been investigated by NMR. The presence of weak and broad zero-field 55Mn resonance, corresponding to internal field of 8–11T, indicates slowing down of spins partially released from the spin-singlet-like state in the spin chains. [Copyright &y& Elsevier]

Abstract: Magnetovolume effects of 3d heavy-electron compounds with linear spin chains, with and , have been investigated to get information on the ground state of and the nature of spin fluctuations in this system. The negative thermal expansion observed for is suppressed by the substitution of a small amount of Y for La. Together with the field-cooled effect in the susceptibility, the magnetovolume effect suggests the development of short-range magnetic correlation in at low temperatures. [Copyright &y& Elsevier]