Research Overview

point contact antenna

The general research theme of our group is nanoscience - new physical phenomena that happen in nanoscale materials and devices, at surfaces and interfaces. Our current areas of interest are spintronics, nanoscale photovoltaics, and surface effects in topological insulators. Physics of electron spin, or spintronics, is the main thrust of our research. Electron spins are at the origin of important phenomena such as magnetism and superconductivity. Nevertheless, the effects of the electron spin on the properties of materials have been often neglected. In the 1980s, researchers started exploring the connection between magnetism and electronic properties of materials and interfaces. Because of the exchange interaction between the magnetic electrons and the conduction electrons, electrical currents through nanoscale magnets can significantly affect their magnetic properties, and vice versa. We are exploring the connection between electronic and magnetic properties of nanoscale structures by a variety of techniques: magnetoelectronic measurements, microwave spectroscopy, optics and in collaboration with other groups by Brillouin light scattering and magnetic dichroism. Below are some snippets of our recent results and ongoing projects.

out-of-plane precession

Microwave Spectroscopy of magnetic dynamics

Synchronization of nanomagnetic oscillators

Left: Dynamical spectra of nanomagnets exhibit a complicated dependence on the magnetic field and electric current driving the dynamics via the spin transfer effect. Right: Nonlinear phase locking of nanomagnetic oscillators, fractional synchronization to external oscillation, Devil’s staircase (top), and hysteretic parametric synchronization (bottom).

Spin waves in nanostructures Spin Wave Interference

emission of spin waves by point contact

Measurements of spin-wave propagation in nanomagnetic structures by Brillouin light scattering performed in collaboration with the group of Sergey Demokritov, University of Muenster, Germany. Left: optical micrograph and spin-wave intensity map in a spin-wave interferometer. Right: emission of spin waves by a point contact.

Photovoltaic nanostructures Schottky diode

Photovoltaics are electronic structures that convert the energy of light into electricity. The propeties of nanoscale photovoltaics are modified by the light interference, plasmonic effects, and quantum confinement. Figure on the left shows our preliminary results for photovoltaic response in nanoscale SChottky junctions.

Surfaces of topological insulators STM impurity

Topological insulators are a special class of materials in which spin-orbit interaction is sufficiently strong to create a robust surface state with a chiral spin-orbit coupled order. Sergei Urazhdin pioneered the studies of the surfaces of topological insulators. The image is an scanning tunneling microscopy map of a subsurface impurity in a topological insulator Bi2Se3.