Current-driven hysteresis effects in manganite spintronics devices

By carrying out differential resistance measurements in oxygen deficient ${\mathrm{La}}_{0.67}{\mathrm{Ba}}_{0.33}\mathrm{Mn}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}$ thin films at different magnetic fields, in submicrometric constricted regions patterned by focused ion beam, we find evidence of hysteretic resistance behavior as a function of both the external magnetic field and dc bias current. The resistance curves exhibit a marked asymmetry with respect to the polarity of the current. We suggest that the spin-polarized injected current exerts a torque on magnetic domains, whose rotation accounts for the hysteretic resistance changes. The memory effect of such constrictions is potentially interesting both for studying micromagnetic effects and in view of spintronics devices applications.