The first topic is the study on the spin dynamics. We are investigating theoretically and experimentally the dynamics of vortices in the lattice configuration with various combinations of vortex core polarizations. The vortex core polarizations are theoretically found to play an important role in determining the rotational dynamics of vortices. Extension of the obtained results encourages us to fabricate an electromagnetic wave guide in the artificial crystal of the magnetic vortex system similar to the two-dimensional photonic crystal.

   The second topic is spin accumulation in the non-local configuration. We have established the experimental techniques to induce spin currents in between ferromagnetic wires bridged by non-magnetic copper wire. This technique has also been applied to non-local spin injection to flip the magnetization of the nano-scale ferromagnetic particle. We have also established the method to calculate the distributions of spin and chargecurrents using the formalism based on the equivalent spin polarized resistor network.

   The third topic is the development of biologically inspired spintronic devices. In this project, we try to manipulate the motion of nano-scale magnetic domain wall and conduction electron spins using the principle of the potential ratchet characteristic of biological systems. The driving force is typically thermal agitation for biological systems. For our spintronic devices, we use the above spin-injection techniques or modulated magnetic field for nano-domain walls, and modulated electric field for rectification of the conduction spins whereby the dc motion of the domain walls and the spins are generated from the ac excitation.

   These studies are carried out both in ISSP (The Institute for Solid State Physics) and RIKEN (The Institute of Physical and Chemical Research).