arXiv subjects

Yaroslav Tserkovnyak

Publications and source records attributed to Yaroslav Tserkovnyak.

223 records · Page 13Linked to original sources

arXiv2002

Shot noise in ferromagnet--normal metal systems

A semiclassical theory of the low frequency shot noise in ferromagnet - normal metal systems is formulated. Non-collinear magnetization directions of the ferromagnetic leads, arbitrary junctions and the elastic and inelastic scattering regimes are considered. The shot noise is governed by a set of mesoscopic parameters that are expressed in terms of the microscopic details of the junctions in the circuit. Explicit results in the case of ballistic, tunnel, and diffusive junctions are evaluated. The shot noise, the current and the Fano factor are calculated for a double barrier ferromagnet - normal metal - ferromagnet system. It is demonstrated that the shot noise can have a non-monotonic behavior as a function of the relative angle between the magnetizations of the ferromagnetic reservoirs.

cond-mat.mes-hall↗

arXiv2002

Current and Spin-Torque in Double Tunnel Barrier Ferromagnet - Superconductor - Ferromagnet Systems

We calculate the current and the spin-torque in small symmetric double tunnel barrier ferromagnet - superconductor - ferromagnet (F-S-F) systems. Spin-accumulation on the superconductor governs the transport properties when the spin-flip relaxation time is longer than the transport dwell time. In the elastic transport regime, it is demonstrated that the relative change in the current (spin-torque) for F-S-F systems equals the relative change in the current (spin-torque) for F-N-F systems upon changing the relative magnetization direction of the two ferromagnets. This differs from the results in the inelastic transport regime where spin-accumulation suppresses the superconducting gap and dramatically changes the magnetoresistance [S. Takahashi, H. Imamura, and S. Maekawa, Phys. Rev. Lett. 82, 3911 (1999)]. The experimental relevance of the elastic and inelastic transport regimes, respectively, as well as the reasons for the change in the transport properties are discussed.

cond-mat.mes-hall↗

arXiv2002

Enhanced Gilbert Damping in Thin Ferromagnetic Films

Using a scattering matrix approach, the precession of the magnetization of a ferromagnet is shown to transfer spins into adjacent normal metal layers. This ``pumping'' of spins slows down the precession corresponding to an enhanced Gilbert damping factor in the Landau-Lifshitz equation. The damping is expressed in terms of the scattering matrix of the ferromagnet-normal metal interface, which is accessible to model and first-principles calculations. Our estimates for permalloy thin films explain the trends observed in recent experiments.

cond-mat.mes-hall↗

arXiv2002

Finite-size effects in tunneling between parallel quantum wires

We present theoretical calculations and experimental measurements which reveal finite-size effects in the tunneling between two parallel quantum wires, fabricated at the cleaved edge of a GaAs/AlGaAs bilayer heterostructure. Observed oscillations in the differential conductance, as a function of bias voltage and applied magnetic field, provide direct information on the shape of the confining potential. Superimposed modulations indicate the existence of two distinct excitation velocities, as expected from spin-charge separation.

cond-mat.mes-hall↗

arXiv2002

Spin battery operated by ferromagnetic resonance

Precessing ferromagnets are predicted to inject a spin current into adjacent conductors via Ohmic contacts, irrespective of a conductance mismatch with, for example, doped semiconductors. This opens the way to create a pure spin source spin battery by the ferromagnetic resonance. We estimate the spin current and spin bias for different material combinations.

cond-mat.mes-hall↗

arXiv2002

Universal angular magnetoresistance and spin torque in ferromagnetic/normal metal hybrids

The electrical resistance of ferromagnetic/normal-metal (F/N) heterostructures depends on the nature of the junctions which may be tunnel barriers, point contacts, or intermetallic interfaces. For all junction types, the resistance of disordered F/N/F perpendicular spin valves as a function of the angle between magnetization vectors is shown to obey a simple universal law. The spin-current induced magnetization torque can be measured by the angular magnetoresistance of these spin valves. The results are generalized to arbitrary magnetoelectronic circuits.

cond-mat.mes-hall↗

arXiv2002

A Three-Dimensional Calculation of Atmospheric Neutrino Fluxes

We present a three-dimensional calculation of atmospheric neutrino fluxes using accurate models of the geomagnetic field, hadronic interactions, tracking and decays. Results are presented for the Super-Kamiokande (SK) and Sudbury Neutrino Observatory (SNO) sites using the GEANT-FLUKA hadronic code. We make a comparison with previous one-dimensional calculations and other three-dimensional results. The recently reported geometrical enhancement of low energy, horizontal neutrinos is confirmed. The effect on observed leptons is however, restricted to a small overall increase in flux. We report east-west asymmetries for each of the neutrino species.

hep-ph↗