Magnetization reversal in individual Py and CoFeB nanotubes locally probed via anisotropic magnetoresistance and anomalous Nernst effect

Abstract

Using anisotropic magnetoresistance in a multi-probe configuration and local heating with a scanning laser, we investigate the magnetization reversal of individual permalloy (Py) and CoFeB nanotubes with spatial resolution. Nanocrystalline Py and amorphous CoFeB nanotubes are found to reverse via domain wall movement and chirality switching, respectively. Our experiments provide an understanding of the role of microstructure and magnetic anisotropy in the switching of ferromagnetic nanotubes at room temperature.

Anomalous Nernst effect in Ir22Mn78/Co20Fe60B20/MgO layers with perpendicular magnetic anisotropy

“…21 A typical setup, utilizing an out-of-plane temperature gradient and an in-plane magnetic field, has been used to investigate the ANE in previous works. [22][23][24][25][26] The trouble with this configuration is that, in addition to generating an ANE voltage, the out-of-plane temperature gradient can also generate a spin current through the so-called longitudinal spin Seebeck effect (LSSE), 22,[27][28][29][30][31][32][33] which flows directly from the ferromagnetic (FM) into the adjacent non-magnetic metal (NM) and generates a voltage because of the inverse spin Hall effect (ISHE). In order to distinguish the spin Seebeck effect (SSE) and ANE, extensive efforts [34][35][36][37] have been made to compare the voltage in different temperature gradient configurations.…”

Imaging magnetic vortex configurations in ferromagnetic nanotubes

“…Scanning electron micrographs (SEMs) of the 19 CoFeB and 25 permalloy (Py) NTs studied [26] reveal continuous surfaces, which are free of detectable defects and whose roughness is less than 5 nm. The fabrication process and choice of materials avoids magneto-crystalline anisotropy [27][28][29], although recent magnetotransport experiments suggest that a growth-induced magnetic anisotropy may be present in the CoFeB NTs [30]. DCM measurements of NTs from the same growth wafers as used here provide μ 0 M S = 1.3 ± 0.1 T and 0.8 ± 0.1 T for the CoFeB [31] and Py [32] NTs, respectively, where μ 0 is the permeability of free space.…”

Imaging Stray Magnetic Field of Individual Ferromagnetic Nanotubes

“…CoFeB is magnetron-sputtered onto template GaAs nanowires (NWs) to produce an amorphous and homogeneous shell [16], which is designed to avoid magneto-crystalline anisotropy [29][30][31]. Nevertheless, recent magneto-transport experiments show that a small growth-induced magnetic anisotropy may be present [20]. Scanning electron micrographs (SEMs) of the studied FNTs, as in Fig.…”