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The influence of rare earth site substitution on structural, transport and magnetic characteristics of polycrystalline Ln 2 CoMnO 6 (Ln = La, Sm and Gd) has been systematically investigated in details. The room temperature X-ray diffraction data confirm the monoclinic crystal structure of the samples, having P2 1 /n space group. The magnetic study reveals that the ferromagnetic transition temperature (T C1  ∼ 233.2 K) of La 2 CoMnO 6 decreases very fast due to a decrease of ionic radii in Ln site and T C2 (∼150 K) disappears in the Gd 2 CoMnO 6 system due to the presence of only Co 2+ and Mn 4+ ion pair. The field dependent magnetization data at 5 K exhibit antiferromagnetic ordering induced in the Sm 2 CoMnO 6 and Gd 2 CoMnO 6 systems due to structural distortion and 4f-3d negative magnetic interactions. The temperature dependent resistivity data of La 2 CoMnO 6 display semiconductor like behavior in a temperature range of 150–300 K and this behavior has been best described by the variable range hopping conduction mechanism. On the other hand, the resistivity of Sm and Gd based samples follows variable range hopping model in the temperature range of 200–300 K. Large magnetoresistance of ∼−26.35% has been observed at 160 K at a magnetic field of 60 kOe in La 2 CoMnO 6 and it decreases to −8.28% for Sm 2 CoMnO 6 , and −1.01% for Gd 2 CoMnO 6 as ionic radii decrease at the Ln site. [ABSTRACT FROM AUTHOR]

We present results of first-principles calculations on the transport properties, both under an electric field or a temperature gradient, in Co/Cu multilayered systems. The various effects brought about by the changes in the morphological parameters, such as the number of repeats and the layer thickness, are discussed in a systematic way. Our calculations show that the Seebeck coefficient and the magneto-thermopower (MTP) converge rather rapidly with the number of Co repeats. In the range of thin Co layers, we find strong variations in the amplitude and sign of both the Seebeck coefficient and the MTP. These large variations, which have no correspondent in the (magneto)conductance, are shown to be the result of quantum well states present in the minority spin channel of thin Co layers.

The Fermi surface of the isostructural organic metals (ET)8Hg4Cl12(C6H5X)2, where X=Cl, Br provides a two-dimensional (2D) network of compensated electron and hole quasi-2D orbits. Interlayer magnetoresistance and magnetisation of these compounds have been investigated in pulsed magnetic fields extending up to 60 and 33 T, respectively. About 15 frequencies, composed of linear combinations of only three basic frequencies, are observed in the oscillatory spectra of the magnetoresistance. A quantum interferometer enclosing an area equal to the first Brillouin zone area is evidenced and consistently accounted for by the conventional 2D Lifshits–Kosevich model. If this model formally accounts for almost all of the observed oscillatory components, it fails to give consistent quantitative data in most other cases which points to the unconventional nature of these oscillations. [Copyright &y& Elsevier]