A Possible way to observe the breathing mode of magnetic domain wall

磁壁のブリージングモードを観測する方法

森 道康  ; 小椎八重 航*; 挽野 真一*; 前川 禎通

Mori, Michiyasu; Koshibae, Wataru*; Hikino, Shinichi*; Maekawa, Sadamichi

We theoretically propose how to observe the breathing mode by the Josephson junction having a ferromagnetic layer between superconducting electrodes. The current-voltage (I-V) curve is calculated by an equivalent circuit of the resistively shunted junction model. The breathing mode is identified by stepwise structures in the I-V curve, which appear at the voltages V=n(/2e) with the fundamental constant /2e, integer number n, and the frequency of the breathing mode. This is the most feasible method to observe the breathing mode of the DW due to the sensitivity of the Josephson junction. In principle, magnetic resonance methods are also possible to measure the breathing mode. However, owing to their low sensitivity, the resonance measurements would be limited to a sample containing huge numbers of DWs or a specific structure of a ferromagnet. Although such a measurement is realized in the Skyrmion lattice, in which the rotational and the breathing modes are observed, it has not been done on the breathing mode of the DW so far. Our method is accessible to the breathing mode of a single DW due to the sensitivity of the Josephson junction.