Abstract We outline the idea of magnetic-field sensing with a nanometer spatial resolution using the effect of giant magnetoreactance (GMX) and we discuss results of our micromagnetic studies of domain-wall-assisted (or double-vortex-assisted) GMX in nanomagnets. By analogy to low-frequency giant magnetoimpedance (GMI), we consider systems of domains magnetized perpendicular to the direction of the AC current that creates an alternating Oersted field, thus, it drives the DW oscillations. Because of small cross-sections, the nanomagnets are not capable to induce large changes of the magnetic flux, therefore, the impedance of magnet-containing nanocircuits is dominated by the static resistivity (in accessible frequency regimes), while, GMX is an alternative effect to be utilized for sensing. We analyze in detail the effect in single-crystalline nanowire of cobalt with the easy axis transverse to the nanowire axis. In that system, small coherent shifts of the domain walls (DWs) induce relatively high changes of the magnetic flux through the largest cross-section of the nanowire due to large density of periodically packed DWs. Driven by the alternating transverse field of the Oersted origin, the system allows for perpendicular (the field directed perpendicular to the long axis of the nanowire and to the domain magnetization) GMX of improved characteristics (the GMX ratio and the field sensitivity of GMX) at a high stability of the magnetic structure in a wide region of the external field. Moreover, due to a non-zero overall magnetization (created by DWs), the perpendicular GMX is strongly asymmetric with respect to the field reversal (in a low-field regime). Also, we study the transverse GMX (the field parallel to the domain magnetization).

中文翻译：

---

磁性纳米线中的巨磁反应

摘要 我们概述了利用巨磁电抗 (GMX) 效应以纳米空间分辨率进行磁场传感的想法，并讨论了我们对纳米磁体中畴壁辅助（或双涡流辅助）GMX 的微磁研究结果。类似于低频巨磁阻抗 (GMI)，我们考虑垂直于 AC 电流方向磁化的磁畴系统，该系统产生交替的奥斯特场，因此，它驱动 DW 振荡。由于横截面小，纳米磁铁不能引起磁通量的大变化，因此，含磁铁的纳米电路的阻抗由静态电阻率决定（在可访问的频率范围内），而 GMX 是一种替代效应用于传感。我们详细分析了易轴横向于纳米线轴的钴单晶纳米线的影响。在该系统中，由于周期性堆积的 DW 密度大，畴壁 (DW) 的小相干位移会导致穿过纳米线最大横截面的磁通量发生相对较高的变化。在奥斯特原点的交替横向场的驱动下，该系统允许垂直（垂直于纳米线长轴和畴磁化方向的场）GMX 具有改进的特性（GMX 比率和 GMX 的场灵敏度）在磁结构在外场较宽区域内的高稳定性。此外，由于非零整体磁化强度（由 DW 产生），垂直 GMX 相对于场反转（在低场区）是强烈不对称的。此外，我们研究了横向 GMX（与磁畴磁化平行的场）。