SFB 767 - TP Z "Central Service"
central activities of the Collaborative Research Center:
colloquia and conferences
lump sum fund
- SFB 767 Kontrollierte Nanosysteme
- FB Physik
|(2016): Dissipation-induced enhancement of quantum fluctuations New Journal of Physics. 2016, 18(5), 053033. eISSN 1367-2630. Available under: doi: 10.1088/1367-2630/18/5/053033||
dc.contributor.author: Rastelli, Gianluca
|(2016): Super-Poissonian Shot Noise of Squeezed-Magnon Mediated Spin Transport Physical Review Letters. 2016, 116(14), 146601. ISSN 0031-9007. eISSN 1079-7114. Available under: doi: 10.1103/PhysRevLett.116.146601||
The magnetization of a ferromagnet (F) driven out of equilibrium injects pure spin current into an adjacent conductor (N). Such F|N bilayers have become basic building blocks in a wide variety of spin-based devices. We evaluate the shot noise of the spin current traversing the F|N interface when F is subjected to a coherent microwave drive. We find that the noise spectrum is frequency independent up to the drive frequency, and increases linearly with frequency thereafter. The low frequency noise indicates super-Poissonian spin transfer, which results from quasiparticles with effective spin ℏ* = ℏ(1 + δ). For typical ferromagnetic thin films, δ ∼ 1 is related to the dipolar interaction-mediated squeezing of F eigenmodes.
|(2016): Photon-assisted electronic and spin transport in a junction containing precessing molecular spin Physical Review B. 2016, 93(7), 075402. ISSN 2469-9950. eISSN 2469-9969. Available under: doi: 10.1103/PhysRevB.93.075402||
We study the ac charge and -spin transport through an orbital of a magnetic molecule with spin precessing in a constant magnetic field. We assume that the source and drain contacts have time-dependent chemical potentials. We employ the Keldysh nonequilibrium Green’s functions method to calculate the spin and charge currents to linear order in the time-dependent potentials. The molecular and electronic spins are coupled via exchange interaction. The time-dependent molecular spin drives inelastic transitions between the molecular quasienergy levels, resulting in a rich structure in the transport characteristics. The time-dependent voltages allow us to reveal the internal precession time scale (the Larmor frequency) by a dc conductance measurement if the ac frequency matches the Larmor frequency. In the low-ac-frequency limit the junction resembles a classical electric circuit. Furthermore, we show that the setup can be used to generate dc-spin currents, which are controlled by the molecular magnetization direction and the relative phases between the Larmor precession and the ac voltage.
|(2016): Electron and electron-hole quasiparticle states in a driven quantum contact Physical Review B. 2016, 93(4), 041416. ISSN 2469-9950. eISSN 2469-9969. Available under: doi: 10.1103/PhysRevB.93.041416||
We study the many-body electronic state created by a time-dependent drive of a mesoscopic contact. The many-body state is expressed manifestly in terms of single-electron and electron-hole quasiparticle excitations with the amplitudes and probabilities of creation which depend on the details of the applied voltage. We experimentally probe the time dependence of the constituent electronic states by using an analog of the optical Hong-Ou-Mandel correlation experiment where electrons emitted from the terminals with a relative time delay collide at the contact. The electron wave packet overlap is directly related to the current noise power in the contact. We have confirmed the time dependence of the electronic states predicted theoretically by measurements of the current noise power in a tunnel junction under harmonic excitation.
|Laufzeit:||01.01.2008 – 31.12.2011|