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All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license.-- et al. ; We report a systematic study on the thermoelectric performance of spin Seebeck devices based on Fe3O4/Pt junction systems. We explore two types of device geometries: a spin Hall thermopile and spin Seebeck multilayer structures. The spin Hall thermopile increases the sensitivity of the spin Seebeck effect, while the increase in the sample internal resistance has a detrimental effect on the output power. We found that the spin Seebeck multilayers can overcome this limitation since the multilayers exhibit the enhancement of the thermoelectric voltage and the reduction of the internal resistance simultaneously, therefore resulting in significant power enhancement. This result demonstrates that the multilayer structures are useful for improving the thermoelectric performance of the spin Seebeck effect. ; This work was supported by the Spanish Ministry of Science (through Project Nos. PRI-PIBJP-2011-0794 and MAT2011-27553-C02, including FEDER funding), the Aragón Regional Government (Project No. E26), Thermo-spintronic Marie-Curie CIG (Grant Agreement No. 304043), JST-PRESTO "Phase Interfaces for Highly Ecient Energy Utilization" from JST, Japan, Grant in-Aid for Scientific Research on Innovative Areas "Nano-Spin Conversion Science" (Grant No. 26103005), Grant-in-Aid for Challenging Exploratory Research (Grant No. 26600067), Grant-inAid for Scientific Research (A) (Grant No. 15H02012) from MEXT, Japan, NEC Corporation, and The Noguchi Institute. ; Peer Reviewed

Under the terms of the Creative Commons Attribution 3.0 Unported License to their work.-- et al. ; We report the experimental observation of the spin Seebeck effect in magnetite thin films. The signal observed at temperatures above the Verwey transition is a contribution from both the anomalous Nernst (ANE) and spin Seebeck (SSE) effects. The contribution from the ANE of the Fe3O 4 layer to the SSE is found to be negligible due to the resistivity difference between Fe3O4 and Pt layers. Below the Verwey transition, the SSE is free from the ANE of the ferromagnetic layer and it is also found to dominate over the ANE due to magnetic proximity effect on the Pt layer. © 2013 American Institute of Physics. ; This work was supported by the Spanish Ministry of Science (through projects PLE2009-0017, PRI-PIBJP-2011-0794, MAT2011-27553-C02, including FEDER funding) and the Aragón Regional Government (project E26). This research was supported by Strategic International Cooperative Program, Japan Science and Technology Agency (JST), PRESTO-JST "Phase Interfaces for Highly Efficient Energy Utilization," CREST-JST "Creation of Nanosystems with Novel Functions through Process Integration," a Grant-in-Aid for Research Activity Start-up (24860003) from MEXT, Japan, a Grant-in-Aid for Scientific Research (A) (24244051) from MEXT, Japan, LC-IMR of Tohoku University, the Murata Science Foundation, and the Mazda Foundation. ; Peer Reviewed

The dependence of Spin Seebeck effect (SSE) with the thickness of the magnetic materials is studied by means of incoherent thermal excitation. The SSE voltage signal in Fe3O4/Pt bilayer structure increases with the magnetic material thickness up to 100 nm, approximately, showing signs of saturation for larger thickness. This dependence is well described in terms of a spin current pumped in the platinum film by the magnon accumulation in the magnetic material. The spin current is generated by a gradient of temperature in the system and detected by the Pt top contact by means of inverse spin Hall effect. Calculations in the frame of the linear response theory adjust with a high degree of accuracy the experimental data, giving a thermal length scale of the magnon accumulation (Λ) of 17 ± 3 nm at 300 K and Λ = 40 ± 10 nm at 70 K. ; This work was supported by the Spanish Ministry of Science (through Project No. MAT2014-51982-C2-R, including European social fund), the Aragon Regional government (Project No. E26), and Thermo-Spintronic Marie Curie CIG Project (Grant Agreement No. 304043). ; Peer Reviewed

We report the disentanglement of bulk and interfacial contributions to the thermally excited magnon spin current in the spin Seebeck effect under static heating. For this purpose, we have studied the dependence of the inverse spin Hall voltage and the thermal conductivity on the magnetic layer thickness. Knowledge of these quantities allows us to take into account the influence of both sources of thermal spin current in the analysis of the voltage dependence. The magnetic layer thickness modulates the relative magnitude of the involved thermal drops for a fixed total thermal difference throughout the sample. In the end, we attain the separate contributions of both sources of thermal spin current—bulk and interfacial—and obtain the value of the thermal magnon accumulation length scale in maghemite, which we find to be 29(1) nm. According to our results, bulk magnon accumulation dominates the spin Seebeck effect in our studied range of thicknesses, but the interfacial component is by no means negligible. ; This work was supported by the Spanish Ministry of Science [through Project Nos. MAT2014-51982-C2-R, MAT2016-80762-R, MAT2017-82970-C2-R, and PID2019-104150RB-I00 (including FEDER funding) and the Aragón Regional government (Project No. E26)]. P.J.-C. acknowledges Spanish MECD for support through FPU program (Reference No. FPU014/02546). D.B. acknowledges support from MINECO (Spain) through an FPI program (No. BES-2017-079688). R.R. also acknowledges support from the European Commission through the Project No. 734187-SPICOLOST (H2020-MSCA-RISE-2016), the European Union's Horizon 2020 research and innovation program through the Marie Sklodowska-Curie Actions Grant Agreement SPEC No. 894006, and the Spanish Ministry of Science (No. RYC 2019-026915-I). Authors acknowledge the Advanced Microscopy Laboratory-INA University of Zaragoza for offering access to their instruments. C. L-B. acknowledges Xunta de Galicia and ESF for a PhD Grant (ED481A-2018/013). ; Peer reviewed

We report temperature dependent measurements of the spin Seebeck effect (SSE) in multilayers formed by repeated growth of a FeO/Pt bilayer junction. The magnitude of the observed enhancement of the SSE, relative to the SSE in the single bilayer, shows a monotonic increase with decreasing the temperature. This result can be understood by an increase of the characteristic length for spin current transport in the system, in qualitative agreement with the recently observed increase in the magnon diffusion length in FeO at lower temperatures. Our result suggests that the thermoelectric performance of the SSE in multilayer structures can be further improved by careful choice of materials with suitable spin transport properties. ; This work was supported by the Spanish Ministry of Science (through projects MAT2014-51982-C2-R, including FEDER funding), the Aragón Regional Government (project E26), Thermo-spintronic Marie-Curie CIG (Grant Agreement No. 304043), JST-PRESTO "Phase Interfaces for Highly Efficient Energy Utilization" from JST, Japan, Grant-in-Aid for Scientific Research on Innovative Areas "Nano Spin Conversion Science" (26103005), Grant-in-Aid for Scientific Research (A) (15H02012) from MEXT, Japan, NEC Corporation, and The Noguchi Institute. T.K. is supported by JSPS through a research fellowship for young scientists (15J08026). ; Peer Reviewed

The spin Peltier effect (SPE), heat-current generation as a result of spin-current injection, has been investigated in alternately stacked Pt/Fe3O4 multilayer films. The temperature modulation induced by the SPE in the [Pt/Fe3O4]×n films was found to be significantly enhanced with increasing the number of Pt/Fe3O4 bilayers n. This SPE enhancement is much greater than that expected for a simple stack of independent Pt/Fe3O4 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. ; This work was supported by PRESTO "Phase Interfaces for Highly Efficient Energy Utilization" (Grant No. JPMJPR12C1) and ERATO "Spin Quantum Rectification Project" (Grant No. JPMJER1402) from JST, Japan; Grantin-Aid for Scientific Research (A) (Grant No. JP15H02012) and Grant-in-Aid for Scientific Research on Innovative Area, "Nano Spin Conversion Science" (Grant No. JP26103005), from JSPS KAKENHI, Japan; the NEC Corporation; the Noguchi Institute; E-IMR, Tohoku University; H2020-MSCARISE-2016 SPICOLOST (Grant No. 734187); the Spanish Ministry of Economy and Competitiveness (Grant No. MAT2014-51982-C-R, including FEDER), Spain; and the Aragon regional government (E26), Spain. S.D. is supported by JSPS through a research fellowship for young scientists (Grant No. JP16J02422). ; Peer reviewed

The extraction conditions and chromatographic analysis from seeds of Inga edulis were optimized and provided one anthocyanin from aqueous fraction and a mixture of three anthocyanins from methanolic fraction. The pure anthocyanin obtained was subjected to structural modifications and the products obtained were subjected to chemical and pharmacological assays, as well as quantum chemical calculations based on DFT and TD-DFT methods. Hence, the anthocyanin fractions were evaluated for their chemical-pharmacological potential through chemical and biological assays: antioxidant activity by the DPPH, determination of the Solar Protection Factor (SPF) and cytotoxic activity (hepatocellular carcinoma infected with hepatitis C virus). The results indicated that even the anthocyanin and derivatized compounds having high antioxidant potential showed an SPF lower than six, which is lower than the minimum accepted by current Brazilian legislation. In addition, none of compounds presented significant cytotoxic activity against the tumour cell line studied.

We report the fabrication of high crystal quality epitaxial thin films of maghemite (γ−Fe2O3), a classic ferrimagnetic insulating iron oxide. Spin Seebeck effect (SSE) measurements in γ−Fe2O3/Pt bilayers as a function of sample preparation conditions and temperature yield a SSE coefficient of 0.5(1) µV/K at room temperature. Dependence on temperature allows us to estimate the magnon diffusion length in maghemite to be in the range of tens of nanometers, in good agreement with that of conducting iron oxide magnetite (Fe3O4), establishing the relevance of spin currents of magnonic origin in magnetic iron oxides. ; This work was supported by the Spanish Ministry of Science (through Project Nos. MAT2014- 51982-C2-R and C1-R, including FEDER funding) and the Aragon Regional government (Project ´ No. E26). Pilar Jimenez-Cavero acknowledges Spanish MECD for support through FPU program ´ (Reference No. FPU014/02546). The authors acknowledge the Advanced Microscopy LaboratoryINA University of Zaragoza for offering access to their instruments. This work was supported by PRESTO "Phase Interfaces for Highly Efficient Energy Utilization" and ERATO "Spin Quantum Rectification" from JST, Japan, Grant-in-Aid for Scientific Research (A) (No. 15H02012), Grant-inAid for Scientific Research on Innovative Area, "Nano Spin Conversion Science" (No. 26103005) from MEXT, Japan, NEC Corporation, and the Noguchi Institute. ; Peer reviewed