Crossover of magnetoresistance from positive to negative in La0.5Sr0.5CoO3 − σ/Si heterostructure

The magnetoresistance (MR) properties of a heterostructure fabricated by depositing a La0.5Sr0.5CoO3 − σ film on an n-type Si substrate have been studied. The heterostructure exhibits a good rectifying behavior. A negative MR at T = 210 K and a positive MR at T = 300 K are observed for all bias currents whereas; for temperatures ranging from 240 to 280 K the MR changes from being positive to negative with the increase of the bias current. The observed behavior of the MR effect is discussed in terms of current-induced ferromagnetic spin order.

► Conducting LaSrCoO semiconductor with a ferromagnetic–paramagnetic transition temperature of about 180 K. ► Heterostructure with a rectification ratio around 22 at 2.5 V and 210 K. ► Crossover from positive to negative magnetoresistance with increasing bias current observed over the temperature range of 240–280 K.