We report a complete characterization of the anomalous Nernst effect (ANE) and its relationship with the anomalous Hall effect (AHE) in Fe 3 O 4 . By combining full thermoelectric and electric transport measurements as a function of temperature, we have verified that the universal scaling relation between the anomalous Hall and diagonal conductivities (σ zy ∝ σ 1.6 zz ), observed in materials with bad-metal-hopping type of conduction, is also applicable to the thermoelectric transport. We further show that the ANE and AHE are commonly related through the Mott relation, therefore demonstrating its validity for anomalous transport phenomena in materials with conduction in the the dirty regime.

Electric properties D 8000CaMn1-xNbxO3 (x ≤ 0.08) Perovskite-Type Phases as Promising New High-Temperature n-Type Thermoelectric Materials. -Title compounds with x = 0.02, 0.05, and 0.08 are synthesized from aqueous solutions of Ca(NO3)2, Mn(NO3)2, citric acid, and Nb2Cl5 (353 K, 3 h, followed by sintering in air at 1473 K for 5 h) and by solid state reactions of stoichiometric amounts of CaCO3, MnO2, and Nb2O5 (1673 K, 6 h). The products are characterized by powder XRD (orthorhombic space group Pnma), HRTEM, SEM, XPS, and thermoelectric properties measurements. Differences in electrical transport and thermal properties are correlated with different microstructures obtained by the two synthesis methods. In the high-temperature range, the materials exhibit large absolute Seebeck coefficient and low electrical resistivity values, resulting in a high power factor. Lower thermal conductivity values are achieved for the wet-chemically derived phases compared to the solid state reaction compounds. ZT (figure of merit) values of >0.3 make these phases the best perovskite-type candidates as n-type polycrystalline thermoelectric materials operating in air at high temperatures. -(BOCHER, L.; AGUIRRE, M. H.; LOGVINOVICH, D.; SHKABKO, A.; ROBERT, R.; TROTTMANN, M.; WEIDENKAFF*, A.; Inorg. Chem. 47 (2008) 18, 8077-8085; Solid State Chem. Catal., EMPA, CH-8600 Duebendorf, Switz.; Eng.) -W. Pewestorf 49-014

The spin Peltier effect (SPE), heat-current generation as a result of spin-current injection, has been investigated in alternately stacked Pt/Fe 3 O 4 multilayer films. The temperature modulation induced by the SPE in the [Pt/Fe 3 O 4 ] × n films was found to be significantly enhanced with increasing the number of Pt/Fe 3 O 4 bilayers n. This SPE enhancement is much greater than that expected for a simple stack of independent Pt/Fe 3 O 4 bilayers. The observed n dependence of the SPE can be explained by introducing spin-current redistribution in the multilayer films in the thickness direction, in a manner similar to the enhancement of the spin Seebeck effect in multilayers.

We report thermoelectric power experiments in e-doped thin films of SrTiO 3 (STO) which demonstrate that the electronic band degeneracy can be lifted through defect management during growth. We show that even small amounts of cationic vacancies, combined with epitaxial stress, produce a homogeneous tetragonal distortion of the films, resulting in a Kondo-like resistance upturn at low temperature, large anisotropic magnetoresistance, and nonlinear Hall effect. Ab initio calculations confirm a different occupation of each band depending on the degree of tetragonal distortion. The phenomenology reported in this Letter for tetragonally distorted e-doped STO thin films, is similar to that observed in LaAlO 3 =STO interfaces and magnetic STO quantum wells. DOI: 10.1103/PhysRevLett.115.166801 PACS numbers: 73.50.-h, 75.47.Lx, 77.84.Bw The possibility of growing epitaxial interfaces with atomic precision leads to unexpected functionalities in polar interfaces between oxide insulators [1][2][3]. In particular, the two-dimensional electron gas (2DEG) emerging at the interface between SrTiO 3 (STO) and LaAlO 3 (LAO) [4,5], can be tuned to produce a very rich phase diagram, including magnetism and superconductivity [6,7]. These properties are common to the 2DEGs stabilized at the bare surface of bulk STO, and are derived to a large extent from the arrangement and filling of the Ti-t 2g -derived subbands close to the conduction band minimum [8][9][10][11]. This orbital reconstruction can be intrinsic, to cancel the electrostatic energy of the polar interface [12], but could also be caused by the structural distortions and atomic vacancies which relax the epitaxial strain in these thin-film heterostructures. However, the effect of cationic and anionic vacancies on the transport properties of both STO [13] and LAO/STO interfaces [14] is mostly considered from the point of view of their acceptor or donor nature over the total charge density, although vacancies distribute along the crystal structure expanding the unit cell due to an increased Coulomb repulsion [15]. In the case of epitaxial thin films below a certain critical thickness, this has to be necessarily accommodated purely as an increase of the c-axis parameter, due to the clamping of the in-plane lattice parameters to the substrate [16]. In this case, if the tetragonal distortion is homogeneous throughout the film instead of localized around defects, an important effect over the band structure can be anticipated.Here we show that the formation of cation or anion vacancies during epitaxial growth results in a homogeneous tetragonal distortion along the films, which determines their transport properties. Ab initio calculations and thermoelectric power experiments under different degrees of stress suggest that the band degeneracy characteristic of STO can be lifted for sufficiently distorted films. A resistance upturn at low temperature, large anisotropic magnetoresistance (AMR), and a nonlinear Hall effect are observed. This phenomenology was previously observed in...

The electroformation and resistance switching behavior of Al/ SrTiO 3−x N y / Al have been investigated. The resistance of Al/ SrTiO 3−x N y / Al irreversibly increases when voltages higher than a certain threshold voltage are applied. A bistable resistance switching develops at one of the Al electrodes that performs as the anode. The formation of stacking faults in SrTiO 3−x N y during preparation by microwave plasma treatment is a prerequisite for the occurrence of switching as confirmed by site-specific high resolution transmission electron microscopy at the electrode interfaces. The resistance switching effect is discussed by considering the role of stacking fault defects in the oxygen/nitrogen diffusion at the anode metal-oxynitride interface.