26 research outputs found
Vanishing Meissner effect as a hallmark of in-plane FFLO instability in superconductor - ferromagnet layered systems
We demonstrate that in a wide class of multilayered superconductor -
ferromagnet structures (e.g., S/F, S/F/N and S/F/F') the vanishing Meissner
effect signals the appearance of the in-plane Fulde-Ferrell-Larkin-Ovchinnikov
(FFLO) modulated superconducting phase. In contrast to the bulk superconductors
the FFLO instability in these systems can emerge at temperatures close to the
critical one and is effectively controlled by the S layer thickness and the
angle between magnetization vectors in the F/F' bilayers. The predicted FFLO
state reveals through the critical temperature oscillations vs the
perpendicular magnetic field component.Comment: 5 pages, 5 figure
Physical Limits of the ballistic and non-ballistic Spin-Field-Effect Transistor: Spin Dynamics in Remote Doped Structures
We investigate the spin dynamics and relaxation in remotely-doped two
dimensional electron systems where the dopants lead to random fluctuations of
the Rashba spin-orbit coupling. Due to the resulting random spin precession,
the spin relaxation time is limited by the strength and spatial scale of the
random contribution to the spin-orbit coupling. We concentrate on the role of
the randomness for two systems where the direction of the spin-orbit field does
not depend on the electron momentum: the spin field-effect transistor with
balanced Rashba and Dresselhaus couplings and the (011) quantum well. Both of
these systems are considered as promising for the spintronics applications
because of the suppression of the Dyakonov-Perel' mechanism there makes the
realization of a spin field effect transistor in the diffusive regime possible.
We demonstrate that the spin relaxation through the randomness of spin-orbit
coupling imposes important physical limitations on the operational properties
of these devices.Comment: 10 pages, 4 figure
Non-exponential spin relaxation in magnetic field in quantum wells with random spin-orbit coupling
We investigate the spin dynamics of electrons in quantum wells where the
Rashba type of spin-orbit coupling is present in the form of random nanosize
domains. We study the effect of magnetic field on the spin relaxation in these
systems and show that the spatial randomness of spin-orbit coupling limits the
minimum relaxation rate and leads to a Gaussian time-decay of spin polarization
due to memory effects. In this case the relaxation becomes faster with increase
of the magnetic field in contrast to the well known magnetic field suppression
of spin relaxation.Comment: published version, minor change
Spin relaxation in quantum dots with random spin-orbit coupling
We investigate the longitudinal spin relaxation arising due to spin-flip
transitions accompanied by phonon emission in quantum dots where the strength
of the Rashba spin-orbit coupling is a random function of the lateral
(in-plane) coordinate on the spatial nanoscale. In this case the Rashba
contribution to the spin-orbit coupling cannot be completely removed by
applying a uniform external bias across the quantum dot plane. Due to the
remnant random contribution, the spin relaxation rate cannot be decreased by
more than two orders of magnitude even when the external bias fully compensates
the regular part of the spin-orbit coupling.Comment: 13 pages, 4 figure