Permanent magnetism, magnetic anisotropy, and hysteresis of thiol-capped gold na

2020-02-14 23:19:42

magnetic nanoparticles Au hysteresis capped

责任者: Crespo, P.;Litran, R.;Rojas, T.C.;Multigner, M.;de la Fuente, J.M.;Sanchez-Lopez, J.C.;Garcia, M.A.;Hernando, A.;Penades, S.;Fernandez, A. 单位: Instituto de Magnetismo Aplicado, CSIC, Madrid, Spain 来源出处: Physical Review Letters(Phys. Rev. Lett. (USA)),2004/08/20,93(8):087204-1 摘要: We report on the experimental observation of magnetic hysteresis up to room temperature in thiol-capped Au nanoparticles with 1.4 nm size. The coercive field ranges from 860 Oe at 5 K to 250 Oe at 300 K. It is estimated that the Au atoms exhibit a magnetic moment of μ=0.036μB. However, Au nanoparticles with similar size but stabilized by means of a surfactant, i.e., weak interaction between protective molecules and Au surface atoms, are diamagnetic, as bulk Au samples are. The apparent ferromagnetism is consequently associated with 5d localized holes generated through Au-S bonds. These holes give rise to localized magnetic moments that are frozen in due to the combination of the high spin-orbit coupling (1.5 eV) of gold and the symmetry reduction associated with two types of bonding: Au-Au and Au-S 关键词: gold;magnetic anisotropy;magnetic moments;magnetic particles;magnetisation;nanocomposites;nanoparticles;organic compounds;particle size;permanent magnetism;magnetic anisotropy;hysteresis;thiol-capped Au nanoparticles;magnetic hysteresis;magnetic moment;high spin-orbit coupling;1.4 nm;5 K;300 K;1.5 eV;Au