Stress‐Induced Domain Wall Motion in FeCo‐Based Magnetic Microwires for Realization of Energy Harvesting

Abstract

domains store information states and the information is read by moving the domains. [11,[14][15][16][17][18] Domain wall movement can also be explored for energy harvesting by converting stress into changes in magnetization and thus into electrical voltage. In the energy harvesting investigations reported so far, domain wall motion is accomplished only in multiferroic structures, where stress was induced by providing an electrical energy to the ferroelectric layers. [19][20][21][22][23][24][25] Employing significant amounts of electrical energy, however, defeats the purpose of energy harvesting. Moreover, ceramic ferroelectric layers, like PZT, require high-temperature deposition or postdeposition annealing (>400 °C) under severe oxidation conditions, which inevitably degrade the magnetic properties. [26] Therefore, stress-induced motion of domain walls in pure magnetic films without the use of ferroelectric layers and a supplied energy is a better approach for self-power generation. In the past, amorphous magnetic materials have been studied for domain wall dynamics under stress. [27,28] Pickup of voltage using a pickup coil was used for sensing the domain wall motion. [29][30][31] An analytical model for stress-induced transverse domain wall movement in ferromagnetic nanostripe has also been proposed. [32] In this article, we report that the domain walls in magnetic microwires made of crystalline ferromagnetic films can be moved by merely applying mechanical stress. The key recipes for the successful observation of such domain wall movement are: (i) a magnetic stack of CoNi/Fe 65 Co 35 /CoNi with which we have controlled the microstructures, (ii) an induced magnetic easy axis that we set by the direction of fringing magnetic field during the deposition (see the Supporting Information), and (iii) the use of flexible substrates with which we could enhance the stress delivered to the device from ambient sources, which is otherwise impossible with rigid substrates like Si. With a prototype device, we have shown in this article, the motion of domain walls under applied stress and have harvested energy.

Ultralow magnetostrictive flexible ferromagnetic nanowires

“…1 In comparison to fabricating thin films, obtaining such nanowire arrays without metal residues is not straightforward. In particular, while photolithography and interference lithography processes are compatible with flexible substrates, 21,22 these cannot reach down to single domain nanowires of width 200 nm or below, magnetic nanowires that are of interest for flexible spin circuits. 1 For this work, we employed optimized charge-mitigated e-beam lithography for flexible substrates, e-beam evaporation, and metal lift-off processing.…”

Additive Manufacturing of Magnetostrictive Fe–Co Alloys

“…This phenomenon means that the direction of elongation also changes because of the magnetic domains; that is, the sum of the shape changes due to magnetic domains is the magnetostriction. The extent of magnetostriction is approximately 1 ppm, which is the same magnitude as the thermal expansion coefficient of metal; thus, even small phenomena greatly influence the magnetic properties of magnetostrictive materials, and these materials are expected to have applications in, for example, sensors and actuators [2][3][4][5][6][7].…”

On the Possibility of Developing Magnetostrictive Fe-Co/Ni Clad Plate with Both Vibration Energy Harvesting and Mass Sensing Elements

“…In recent years, Fe-Ga/Fe-Co laminated materials [ 13 ], Fe-Co/piezoelectric laminated materials [ 14 ], Tb-Dy-Fe/Fe-Co laminated materials [ 15 ], Fe-Co coatings [ 16 ], and Fe-Co short wire/polymer composites [ 17 ] have been developed for sensor applications. Stress-induced domain wall motion of Co-based microwires [ 18 ], inverse magnetostrictive characteristics of Fe-Co wire/Al-Si composites under impact loading [ 19 ], and the twisting effect on the energy conversion of Fe-Co wire/Al-Si [ 20 ] and Fe-Co wire/polymer [ 21 ] composites have also been studied. In addition, an Fe-Co bolt with a sensor function has been developed [ 22 ].…”