Gate-induced switching of perpendicular exchange bias with very low coercivity in Pt/Co/Ir/Cr2O3/Pt epitaxial film

Abstract

We investigate magnetoelectric switching of perpendicular exchange bias with very low coercivity in a Pt/Co/Ir/Cr2O3/Pt epitaxial film. We also optimize the suitable Ir spacer thickness so that the film exhibits the perpendicular exchange bias greater than the coercivity up to the vicinity of the Néel temperature. Main impact of the Ir spacer layer is the significant reduction of coercivity less than 0.5 mT in maintaining both the perpendicular magnetic anisotropy and the perpendicular exchange bias. For the suitable structure, the perpendicular exchange bias was isothermally switched by the gate voltage in combination with the magnetic field. Analysis of the hysteresis of the exchange bias field as a function of the gate voltage suggested that the magnetoelectric coefficient was comparable to the reported value. This implies that the Ir layer does not degrade the efficiency to transfer the magnetoelectrically controlled antiferromagnetic order parameter to the ferromagnetic Pt/Co/Ir trilayer.

Study of the Long-Range Exchange Coupling in Nd-Fe-B/Ti/Fe Multilayered Structure

“…Thin films of FM material are separated from each other by a non-magnetic material (spacer layer). A non-magnetic layer with a small thickness plays a crucial role in the FM and AFM coupling between two magnetic thin films [26][27][28][29][30]. The magnetizations of the FM layers separated by the non-magnetic spacer layers are coupled by the electrons in the spacer layers.…”

Ionic control of magnetism in all-solid-state CoOx/yttria-stabilized zirconia heterostructures

“…Magneto-ionics can cause a large nonvolatile modulation of a variety of magnetic properties, such as coercivity, anisotropy, magnetization, exchange bias, domain wall motion, or skyrmion density, even inducing transitions between paramagnetic and ferromagnetic states in some cases. [1][2][3][4][5][6] Most magneto-ionic studies have focused on the effects of triggering the motion of ions from an ion reservoir (e.g., HfO 2 , 7 GdO x , 8 and liquid electrolyte with Li þ in dissolution 9 ) to an adjacent target magneto-ionic film (typically, a ferromagnetic metal or ferrimagnetic transition metal oxide). In addition, we have shown during the last few years, that it is also possible to induce the appearance of ferromagnetic properties starting from initially paramagnetic films that contain the mobile ions (e.g., O 2À or N 3À ) in their structure.…”