Spin-Polarization Transfer in Colloidal Magnetic-Plasmonic Au/Iron Oxide Hetero-nanocrystals

• Published in: ACS nano Vol. 7; no. 1; pp. 857 - 866
• Main Authors: Pineider, Francesco, de Julián Fernández, César, Videtta, Valeria, Carlino, Elvio, al Hourani, Awni, Wilhelm, Fabrice, Rogalev, Andrei, Cozzoli, P. Davide, Ghigna, Paolo, Sangregorio, Claudio
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22.01.2013
• Subjects: Colloids; Colloids - chemistry; Contact; Ferric Compounds - chemistry; Gold; Gold - chemistry; Iron; Iron oxides; Magnetic Fields; Magnetic moment; Magnetization; Materials Testing; Metal Nanoparticles - chemistry; Nanocrystals; Noble metals; Spin Labels; Surface Plasmon Resonance - methods; magneto-plasmonics; core−shell heterostructures; X-ray spectroscopy; spin polarization; colloidal nanocrystals; nanomagnetism
• ISSN: 1936-0851; 1936-086X; 1936-086X
• DOI: 10.1021/nn305459m

We report on the unprecedented direct observation of spin-polarization transfer across colloidal magneto-plasmonic Au@Fe-oxide core@shell nanocrystal heterostructures. A magnetic moment is induced into the Au domain when the magnetic shell contains a reduced Fe-oxide phase in direct contact with the noble metal. An increased hole density in the Au states suggested occurrence of a charge-transfer process concomitant to the magnetization transfer. The angular to spin magnetic moment ratio, m orb/m spin, for the Au 5d states, which was found to be equal to 0.38, appeared to be unusually large when compared to previous findings. A mechanism relying on direct hybridization between the Au and Fe states at the core/shell interface is proposed to account for the observed transfer of the magnetic moment.