9 research outputs found
Robust Perpendicular Exchange Coupling In An Ultrathin Coo/ptfe Double Layer: Strain And Spin Orientation
We report on the exchange coupling and magnetic properties of a strained ultrathin CoO/PtFe double layer with perpendicular magnetic anisotropy. The cobalt oxide growth by reactive molecular beam epitaxy on a Pt-terminated PtFe/Pt(001) surface gives rise to a hexagonal surface and a monoclinic distorted CoO 3 nm film at room temperature. This distorted ultrathin CoO layer couples with the PtFe(001) layer establishing a robust perpendicular exchange bias shift. Soft x-ray absorption spectroscopy provides a full description of the spin orientations in the CoO/PtFe double layer. The exchange bias shift is preserved up to the Néel antiferromagnetic ordering temperature of T N=293 K. This unique example of selfsame value for blocking and ordering temperatures, yet identical to the bulk ordering temperature, is likely related to the original strain-induced distortion and strengthened interaction between the two well-ordered spin layers. © 2013 American Physical Society.8814Chappert, C., Fert, A., Van Dau, F.N., The emergence of spin electronics in data storage (2007) Nature Materials, 6 (11), pp. 813-823. , DOI 10.1038/nmat2024, PII NMAT2024He, X., Wang, Y., Wu, N., Caruso, A., Vescovo, E., Belashchenko, K., Dowben, P., Binek, C., (2010) Nat. Mater., 9, p. 579. , 1476-1122 10.1038/nmat2785Park, B., Wunderlich, J., Marti, X., Holy, V., Kurosaki, Y., Yamada, M., Yamamoto, H., Jungwirth, T., (2011) Nat. Mater., 10, p. 347. , 1476-1122 10.1038/nmat2983Shiratsuchi, Y., Noutomi, H., Oikawa, H., Nakamura, T., Suzuki, M., Fujita, T., Arakawa, K., Nakatani, R., (2012) Phys. Rev. Lett., 109, p. 077202. , PRLTAO 0031-9007 10.1103/PhysRevLett.109.077202Berkowitz, A.E., Takano, K., Exchange anisotropy - A review (1999) Journal of Magnetism and Magnetic Materials, 200 (1), pp. 552-570. , DOI 10.1016/S0304-8853(99)00453-9Meiklejohn, W.H., Bean, C.P., (1956) Phys. Rev., 102, p. 1413. , PHRVAO 0031-899X 10.1103/PhysRev.102.1413Mangin, S., Ravelosona, D., Katine, J.A., Carey, M.J., Terris, B.D., Fullerton, E.E., Current-induced magnetization reversal in nanopillars with perpendicular anisotropy (2006) Nature Materials, 5 (3), pp. 210-215. , DOI 10.1038/nmat1595Roth, W.L., (1958) Phys. Rev., 110, p. 1333. , PHRVAO 0031-899X 10.1103/PhysRev.110.1333Jauch, W., Reehuis, M., Bleif, H.J., Kubanek, F., Pattison, P., (2001) Phys. Rev. B, 64, p. 052102. , PRBMDO 1098-0121 10.1103/PhysRevB.64.052102Schrön, A., Rödl, C., Bechstedt, F., (2012) Phys. Rev. B, 86, p. 115134. , PRBMDO 1098-0121 10.1103/PhysRevB.86.115134Csiszar, S.I., Haverkort, M.W., Hu, Z., Tanaka, A., Hsieh, H.H., Lin, H.-J., Chen, C.T., Tjeng, L.H., Controlling orbital moment and spin orientation in CoO layers by strain (2005) Physical Review Letters, 95 (18), pp. 1-4. , http://oai.aps.org/oai/?verb=ListRecords&metadataPrefix= oai_apsmeta_2&set=journal:PRL:95, DOI 10.1103/PhysRevLett.95.187205, 187205Van Der Zaag, P.J., Ijiri, Y., Borchers, J.A., Feiner, L.F., Wolf, R.M., Gaines, J.M., Erwin, R.W., Verheijen, M.A., (2000) Phys. Rev. Lett., 84, p. 6102. , PRLTAO 0031-9007 10.1103/PhysRevLett.84.6102Maat, S., Takano, K., Parkin, S.S.P., Fullerton, E.E., (2001) Phys. Rev. Lett., 87, p. 087202. , PRLTAO 0031-9007 10.1103/PhysRevLett.87.087202Tonnerre, J.M., De Santis, M., Grenier, S., Tolentino, H.C.N., Langlais, V., Bontempi, E., Garcia-Fernandez, M., Staub, U., Depth magnetization profile of a perpendicular exchange coupled system by soft-X-ray resonant magnetic reflectivity (2008) Physical Review Letters, 100 (15), p. 157202. , http://oai.aps.org/oai?verb=GetRecord&Identifier=oai:aps.org: PhysRevLett.100.157202&metadataPrefix=oai_apsmeta_2, DOI 10.1103/PhysRevLett.100.157202Soares, M.M., De Santis, M., Tolentino, H.C.N., Ramos, A.Y., El Jawad, M., Gauthier, Y., Yildiz, F., Przybylski, M., (2012) Phys. Rev. B, 85, p. 205417. , PRBMDO 1098-0121 10.1103/PhysRevB.85.205417Okamoto, S., Kikuchi, N., Kitakami, O., Miyazaki, T., Shimada, Y., Fukamichi, K., (2002) Phys. Rev. B, 66, p. 024413. , PRBMDO 1098-0121 10.1103/PhysRevB.66.024413Soares, M.M., Tolentino, H.C.N., Santis, M.D., Ramos, A.Y., Cezar, J.C., (2011) J. Appl. Phys., 109, pp. 07D725. , 10.1063/1.3556782Regan, T.J., Ohldag, H., Stamm, C., Nolting, F., Lüning, J., Stöhr, J., White, R.L., (2001) Phys. Rev. B, 64, p. 214422. , PRBMDO 1098-0121 10.1103/PhysRevB.64.214422Wu, J., Park, J.S., Kim, W., Arenholz, E., Liberati, M., Scholl, A., Wu, Y.Z., Qiu, Z.Q., (2010) Phys. Rev. Lett., 104, p. 217204. , PRLTAO 0031-9007 10.1103/PhysRevLett.104.217204Abrudan, R., Miguel, J., Bernien, M., Tieg, C., Piantek, M., Kirschner, J., Kuch, W., (2008) Phys. Rev. B, 77, p. 014411. , PRBMDO 1098-0121 10.1103/PhysRevB.77.014411Lamirand, A.D., Soares, M.M., Santis, M.D., Ramos, A.Y., Tolentino, H.C.N., (unpublished)Mittendorfer, F., Weinert, M., Podloucky, R., Redinger, J., (2012) Phys. Rev. Lett., 109, p. 015501. , PRLTAO 0031-9007 10.1103/PhysRevLett.109.015501Van Der Laan, G., Arenholz, E., Chopdekar, R.V., Suzuki, Y., (2008) Phys. Rev. B, 77, p. 064407. , PRBMDO 1098-0121 10.1103/PhysRevB.77.064407Finazzi, M., Altieri, S., (2003) Phys. Rev. B, 68, p. 054420. , PRBMDO 1098-0121 10.1103/PhysRevB.68.054420Ambrose, T., Chien, C.L., (1996) Phys. Rev. Lett., 76, p. 1743. , PRLTAO 0031-9007 10.1103/PhysRevLett.76.1743Molina-Ruiz, M., Lopeandía, A.F., Pi, F., Givord, D., Bourgeois, O., Rodríguez-Viejo, J., (2011) Phys. Rev. B, 83, p. 140407. , PRBMDO 1098-0121 10.1103/PhysRevB.83.140407Nakajima, N., Koide, T., Shidara, T., Miyauchi, H., Fukutani, H., Fujimori, A., Iio, K., Suzuki, Y., (1998) Phys. Rev. Lett., 81, p. 5229. , PRLTAO 0031-9007 10.1103/PhysRevLett.81.522
Dinâmica de íons em solo ácido lixiviado com extratos de resíduos de adubos verdes e soluções puras de ácidos orgânicos Dynamic of ions in acid soil leached with green manure residues extracts and pure solutions of organic acids
A influência da aplicação de resíduos vegetais na dinâmica de íons em solos ácidos é pouco conhecida. Neste estudo, a mobilidade de íons em amostra do horizonte Bw de um Latossolo Vermelho-Escuro álico lixiviado com soluções puras de ácidos cítrico e succínico e extratos aquosos de resíduos de nabo forrageiro (Raphanus sativus) e aveia-preta (Avena strigosa) foi avaliada em colunas de solo (5, 10, 20 e 40 cm de altura por 4 cm de diâmetro). Após a percolação das soluções e extratos pelas colunas de solo determinaram-se, nas soluções efluentes, os teores de Ca (Ca s), Mg (Mg s), K (Ks), Al total (Al st), orgânico (Al so), monomérico (Al sm) e carbono orgânico dissolvido. No solo, foram determinados os teores trocáveis de Ca (Ca tr), Mg (Mg tr), K (Ktr) e Al (Al tr) e o pH (CaCl2). Os ácidos cítrico e succínico aumentaram os teores de Al st e Ca s, respectivamente, causando reduções nas frações trocáveis desses elementos no solo. O extrato de aveia-preta foi mais efetivo na remoção do Ca tr e o de nabo forrageiro na do Al tr. O decréscimo de Ca tr e Al tr foi seguido do aumento do Ktr. A formação de complexos entre Ca s e Al tr com compostos orgânicos de baixo peso molecular foi sugerida como o provável mecanismo responsável pela mobilidade dos íons polivalentes no subsolo de solos ácidos após a aplicação dos extratos de resíduos vegetais e das soluções puras de ácidos orgânicos.<br>The influence of green manure residues addition in the dynamic of ions in acid soils is not well known. In this study, ion mobility in a sample of the Bw horizon of an Dark-Red Latosol (Oxisol), leached with citric and succinic acid pure solutions and with aqueous residue extracts of black oats (Avena strigosa) and oil seed radish (Raphanus sativus) were evaluated in soil columns (5, 10, 20, and 40 cm long by 4 cm diameter). After the solutions and extracts passed through the soil columns, the following parameters were determined: solubles contents of Ca s, Mg s, Ks, Al st (total), Al so (organic), Al sm (monomeric) and dissolved organic carbon. In soil, the parameters evaluated were the exchangeable contents of Ca ex, Mg ex, Kex, and Al ex and pH (CaCl2). Citric and succinic acids increased Al st and Ca s contents, respectively, resulting in decreasing exchangeable fractions of these elements in soil. Black oats extract was more effective to extract Ca ex and oil seed radish to extract Al ex. The decrease in Ca ex and Al ex was followed by an increase in Kex. Organic complexes formed with low molecular organic ligands and Ca s and Al ex were suggested to play a role in the mobility of ions in subsoils of acid soils after the addition of both crop residues extracts and pure organic acid solutions