Magneto-optical Kerr spectra of gold induced by spin accumulation

We report the magneto-optic Kerr effect (MOKE) angle of Au magnetically excited by spin accumulation. perform time-resolved polar MOKE measurements on Au/Co heterostructures. In our experiment, ultrafast optical excitation Co drives accumulation into an adjacent layer. The accumulation, together with spin-orbit coupling, leads to nonzero terms in off-diagonal conductivity tensor Au, which we measure recording polarization and ellipticity light reflected from surface for photon energies between 1.3 3.1 eV. a narrow energy range near interband transition threshold sensitivity magnetization measured exceeds $1\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{rad}\phantom{\rule{0.28em}{0ex}}\mathrm{per}\phantom{\rule{0.28em}{0ex}}\mathrm{A}/\mathrm{m}$. interval 0.6--4.4 eV, maximum value ferromagnetic metals like Ni are $<10\phantom{\rule{0.28em}{0ex}}\mathrm{nrad}\phantom{\rule{0.28em}{0ex}}\mathrm{per}\phantom{\rule{0.28em}{0ex}}\mathrm{A}/\mathrm{m}$, while predicted values heavy Pt or W $<13\phantom{\rule{0.28em}{0ex}}\mathrm{nrad}\phantom{\rule{0.28em}{0ex}}\mathrm{per}\phantom{\rule{0.28em}{0ex}}\mathrm{A}/\mathrm{m}$. exceptional properties magnetic moments make exceptionally sensitive magnetometer, potential applications development optospintronic technologies.