Exchange bias effect and intragranular magnetoresistance in Nd_0.84Sr_0.16CoO₃

Abstract

Abstract. Electrical transport properties as a function of magnetic field and time have been investigated in polycrystalline, Nd 0.84 Sr 0.16 CoO 3 . A strong exchange bias (EB) effect is observed associated with the fairly large intragranular magnetoresistance (MR). The EB effect observed in the MR curve is compared with the EB effect manifested in magnetic hysteresis loop. Training effect, described as the decrease of EB effect when the sample is successively field-cycled at a particular temperature, has been observed in the shift of the MR curve. Training effect could be analysed by the successful models. The EB effect, MR and a considerable time dependence in MR are attributed to the intrinsic nanostructure giving rise to the varieties of magnetic interfaces in the grain interior.

Exchange bias effect in alloys and compounds

“…The values of H E or M E obtained from the least square fit with λ satisfactorily interpret the experimental data using equation (2) for different cases such as layered structures [102,103,104,105,106,107,108,109,110,111], nanocomposites [112], bulk Heusler alloys [113,114] and oxide compounds [95,98,115,116,117,118,119]. Equation (2) can also satisfactorily interpret the shift of MR curves, exhibiting EB effect [99,120,121].…”

“…for λ ≥ 2. The training effect in magnetic hysteresis loop [98] and MR curve [99] has been shown for Nd 0.8 Sr 0.2 CoO 3 in figures 2 and 3, respectively. The decreases in H E are highlighted by the arrows in the insets of the figures.…”

“…They further proposed that decrease of H E or M E satisfies following empirical formula ). Open circles are experimental data while small filled symbols represent the data obtained from least square fit described in equation ( 2) [reprinted from [99]].…”

“…(Right inset) Plot of H E with λ where solid straight line exhibits the fit by a power law given in equation (1) (In the original figure H E was plotted with λ −0.5 ). Open circles are experimental data while small filled symbols represent the data obtained from least square fit described in equation (2) [reprinted from[99]].…”

“…Inset shows diagrams of the grain interior magnetic nanostructure. FM, PFM and FIM represent the ferromagnetic, pinned ferromagnetic and ferrimagnetic regions [reprinted from[99]].…”