Modulation of exchange bias in Py/IrMn films by surface acoustic waves

【摘要】 We investigate the surface acoustic wave（SAW） modulation of the exchange bias field(H_EB) in Py/IrMn films deposited on LiNbO₃ substrates.We measured the anisotropic magnetoresistance（AMR） of the multilayer film when continuous SAW or pulsed SAW were applied and obtained H_EB.With continuous SAW,the H_EB decreases continuously with power.While in the case of pulsed SAW,the H_EB first decreases and then stabilizes.Compared to pulsed SAW,the thermal effects from the continuous SAW lead to the continuous decrease of H_EB at higher SAW power,which is verified by the measurement of H_EB at different temperatures and input currents.Furthermore,our results show that pulsed SAW can effectively avoid thermal effects.The decrease of H_EB at smaller power in both continuous and pulsed SAW is mainly due to the SAW-induced dynamic strain field,which leads to a small perturbation in the magnetic moment of the FM layer.Combined with the AMR values measured at different angles during the saturation field,we believe that the SAW-induced dynamic strain field causes a 15° angle between the magnetic moment and the easy axis.Our experiments provide a different approach to manipulating H_EB,opening up a potential avenue for future manipulation of antiferromagnetic moments.更多还原

【Abstract】 We investigate the surface acoustic wave（SAW） modulation of the exchange bias field(H_EB) in Py/IrMn films deposited on LiNbO₃ substrates.We measured the anisotropic magnetoresistance（AMR） of the multilayer film when continuous SAW or pulsed SAW were applied and obtained H_EB.With continuous SAW,the H_EB decreases continuously with power.While in the case of pulsed SAW,the H_EB first decreases and then stabilizes.Compared to pulsed SAW,the thermal effects from the continuous SAW lead to the continuous decrease of H_EB at higher SAW power,which is verified by the measurement of H_EB at different temperatures and input currents.Furthermore,our results show that pulsed SAW can effectively avoid thermal effects.The decrease of H_EB at smaller power in both continuous and pulsed SAW is mainly due to the SAW-induced dynamic strain field,which leads to a small perturbation in the magnetic moment of the FM layer.Combined with the AMR values measured at different angles during the saturation field,we believe that the SAW-induced dynamic strain field causes a 15° angle between the magnetic moment and the easy axis.Our experiments provide a different approach to manipulating H_EB,opening up a potential avenue for future manipulation of antiferromagnetic moments.更多还原