Modulation of spin dynamics in Ni/Pb(Mg1/3}Nb2/3})O3-PbTiO3 multiferroic heterostructure

Motivated by the fast-developing spin dynamics in ferromagnetic/piezoelectric structures, this study attempts to manipulate magnons (spin-wave excitations) by the converse magnetoelectric (ME) coupling. Herein, electric field (E-field) tuning magnetism, especially the surface spin wave, is accomplished in Ni/0.7Pb(Mg1/3}Nb2/3})O3—0.3PbTiO3 (PMN—PT) multiferroic heterostructures. The Kerr signal (directly proportional to magnetization) changes of Ni film are observed when direct current (DC) or alternative current (AC) voltage is applied to PMN—PT substrate, where the signal can be modulated breezily even without extra magnetic field (H-field) in AC-mode measurement. Deserved to be mentioned, a surface spin wave switch of “1” (i.e., “on”) and “0” (i.e., “off”) has been created at room temperature upon applying an E-field. In addition, the magnetic anisotropy of heterostructures has been investigated by E-field-induced ferromagnetic resonance (FMR) shift, and a large 490 Oe shift of FMR is determined at the angle of 45° between H-field and heterostructure plane.

Electric-field-tunable linear unipolar magnetic switch based on a spin-valve multiferroic heterostructure

This work reports an energy-efficient strategy for realizing linear unipolar giant magnetoresistance (GMR) switch by using electric fields (E-fields). Herein, a modified spin-valve (SV) structure of double antiferromagnetic (AFM) pinning layers was adopted. Since the magnetization direction of ferromagnetic (FM) layer can be controlled via the strain-mediated magnetoelectric (ME) effect, a multiferroic heterostructure of SV/PMN-PT was fabricated. By applying an E-field on the PMN-PT substrate, an effective magnetic field Heff was produced along the [1-10] direction of PMN-PT. It can turn the magnetic moments of FM layer toward [1-10] direction. Accordingly, a linear GMR curve with a wide sensing field range was achieved. This E-field-induced linear magnetic switch can satisfy the demand for different switching field ranges in the same application system.

Nonvolatile voltage-controlled magnetization reversal in a spin-valve multiferroic heterostructure

Pure voltage-controlled magnetism, rather than a spin current or magnetic field, is the goal for next-generation ultralow power consumption spintronic devices. To advance toward this goal, we report a voltage-controlled nonvolatile 90° magnetization rotation and voltage-assisted 180° magnetization reversal in a spin-valve multiferroic heterostructure. Here, a spin valve with a synthetic antiferromagnetic structure was grown on a (110)-cut Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) substrate, in which only the magnetic moment of the free layer can be manipulated by an electric field (E-field) via the strain-mediated magnetoelectric coupling effect. As a result of selecting a specified PMN-PT substrate with defect dipoles, nonvolatile and stable magnetization switching was achieved by using voltage impulses. Accordingly, a giant, reversible and nonvolatile magnetoresistance modulation was achieved without the assistance of a magnetic field. In addition, by adopting a small voltage impulse, the critical magnetic field required for complete 180° magnetization reversal of the free layer can be tremendously reduced. A magnetoresistance ratio as large as that obtained by a magnetic field or spin current under normal conditions is achieved. These results indicate that E-field-assisted energy-efficient in-plane magnetization switching is a feasible strategy. This work is significant to the development of ultralow-power magnetoresistive memory and spintronic devices.

Modulation of Spin Dynamics in Ni/Pb(Mg1/3Nb2/3)O3-PbTiO3 Multiferroic Heterostructure

Motivated by the fast-developing spin dynamics in ferromagnetic/piezoelectric structures, this work attempts to manipulate magnonics (spin dynamics) by the converse magnetoelectric (ME) coupling. Herein, electric field (E-field) tuning magnetism, especially the surface spin wave, is accomplished in Ni/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) multiferroic heterostructures. The Kerr signal (∝magnetization) changes of Ni film are observed when direct current (DC) or alternative current (AC) voltage is applied to PMN-PT substrate, where the signal can be modulated breezily even with no extra magnetic field (H-field) is needed in AC-mode measurement. Deserved to be mentioned, an “1” (i.e., “on”) and “0” (i.e., “off”) surface spin wave switch upon applying an E-field is created at room temperature. In addition, the magnetic anisotropy of heterostructures has been investigated by E-field induced ferromagnetic resonance (FMR) shift, and a large 490 Oe shift of FMR is determined at the angle of 45° between H-field and heterostructure plane.