CPM Seminar

Order from Disorder: Spin and Charge Transport in Systems with Nanoscale Random Spin-Orbit Coupling

Evgeny Sherman

Department of Physical Chemistry
Universidad del Pais Vasco

Narrow-gap semiconductors show a strong spin-orbit coupling, very sensitive to the material structure and local defects. As a result, any local disorder causes a variation in the spin-orbit coupling field, and a random spin-orbit field pattern is formed. This field with the correlation length on the order of 10 nm, strongly influences kinetic process in the two-dimensional electron gas. We will describe main features of this field and consider several examples, where it leads to new measurable results even if the expectation value of the coupling vanishes.

First, we will consider spin dynamics in one-dimensional nanowires and show that they demonstrate a very strong low-frequency spin noise due to the randomness in the spin-orbit coupling.

Second, we discuss spin injection by periodic external electric field and will see that the injection is efficient even if the expectation value of the random spin-orbit field is zero.

Third, we consider spin-Hall, anomalous Hall and magnetoresistivity effects resulting from this random field. The random spin-orbit coupling leads to negative magnetoresistance as well as to the anisotropic conductivity with a new mechanism due to suppression of spin-flip scattering in external magnetic field.

References:
[1] For a review of the field: M.M. Glazov, E.Ya. Sherman, and V.K. Dugaev, Two-dimensional electron gas with spin�orbit coupling disorder, Physica E: Low-Dimensional Systems and Nanostructures, 42, 2157 (2010).