Controlling the tunnel resistance of suspended Ni nanogaps using field-emission-induced electromigration J. Vac. Sci. Technol. B 33, 02B107 (2015); 10.1116/1.4904731Fabrication of planar-type Ni/vacuum/Ni tunnel junctions based on ferromagnetic nanogaps using field-emissioninduced electromigrationWe present a simple technique for simultaneous control of the electrical properties of multiple Ni nanogaps. This technique is based on electromigration induced by a field emission current and is called "activation." Simultaneous tuning of the tunnel resistance of multiple nanogaps was achieved by passing a Fowler-Nordheim (F-N) field emission current through an initial group of three Ni nanogaps connected in series. The Ni nanogaps, which had asymmetrical shapes with initial gap separations in the 80-110-nm range, were fabricated by electron-beam lithography and a lift-off process. By performing the activation procedure, the current-voltage properties of the series-connected nanogaps were varied simultaneously from "insulating" to "metallic" via "tunneling" properties by increasing the preset current of the activation procedure. We can also simultaneously control the tunnel resistances of the series-connected nanogaps, which range from a resistance of the order of 100 TX-100 kX, by increasing the preset current from 1 nA to 30 lA. This tendency is quite similar to that of individually activated nanogaps, and the tunnel resistance values of the simultaneously activated nanogaps were almost the same at each preset current. These results clearly imply that the electrical properties of the series-connected nanogaps can be controlled simultaneously via the activation procedure. V C 2015 AIP Publishing LLC.