Angular dependence of domain wall resistivity in SrRuO3

Domain Wall Resistivity (DWR) in ferromagnets raised an extent interest in recent years, mainly due to similarity of the situation existing in homogenous magnetic materials with domain walls to that presented in what is known as giant-magnetoresistance (GMR) structures.

We studied an influence of magnetic domain walls on the resistivity in SrRuO₃, which is a 4d itinerant ferromagnet with Tc = 150 K. The ferromagnets are group of metals in which spontaneous magnetization appears when temperature goes below its critical value, (in case of SrRuO₃ the magnetic moment of electrons which are located at a 4d atomic shell contribute to a non-equilibrium magnetization). In this case, small areas are created inside the substance where spin of electrons aligned in the same direction, those areas called magnetic domains. The intrinsic interface between magnetic domains with different magnetization is called magnetic domain wall.

Two important advantages of SrRuO₃ - high magneto-crystalline anisotropy (~ 10 T) and a very low self-field (4PiM = 0.2 T) enabled the measurement of DWR without the influence of additional effects, like Anisotropic Magneto-Resistance (AMR) and Lorentz Magneto-Resistance (LMR).

We measured the DWR in a wide range of temperatures (from 2 K to Tc), with current flowing at eight different angles (0,15, 30, 45, 60, 75, 90 and �45 degree) towards the domain walls.

A simple fit of the angular dependence of DWR was found, and based on the experimental result it was shown that the contribution of a spin accumulation, which is regarded to be one of the main sources of DWR, is likely to behave as sin^2(x), where x is the angle between the electric current and the magnetic domain walls. We also calculated spin accumulation interface resistance and spin diffusion length, and showed that their values are consistent with existent theories.

Publications

Angular dependence of domain wall resistivity in SrRuO₃ films M.Feigenson, L.Klein et al., Phys. Rev. B 67, 134436(2003)

Spin accumulation contribution to domainwall resistivity in SrRuO₃ M.Feigenson, L.Klein et al., was accepted to Journal of Magnetism and Magnetic Materials (2003)