We analyzed the photoluminescence intermittency generated by a single paramagnetic spin localized in an individual semiconductor quantum dot. The statistics of the photons emitted by the quantum dot reflect the quantum fluctuations of the localized spin interacting with the injected carriers. Photon correlation measurements, which are reported here, reveal unique signatures of these fluctuations. A phenomenological model is proposed to quantitatively describe these observations, allowing a measurement of the spin dynamics of an individual magnetic atom at zero magnetic field. These results demonstrate the existence of an efficient spin-relaxation channel arising from a spin exchange with individual carriers surrounding the quantum dot. A theoretical description of a spin-flip mechanism involving spin exchange with surrounding carriers gives relaxation times in good agreement with the measured dynamics.
In this study, we demonstrate that, beyond the standard magnon excitations, the electron-electron interactions in presence of disorder in CoFeB electrodes play a significant role on the zero-bias anomaly measured in CoFeB/MgO/CoFeB junctions. The low-temperature dependence of the tunneling conductance presents cusplike dip at low voltage varying as the square root of the bias voltage. The amplitude of this zero-bias anomaly decreases with the annealing temperature, indicating interface crystallization and related increase in the tunnel magnetoresistance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.