Sensing magnetic fields using superparamagnetic nanomagnets
Sensing magnetic fields using superparamagnetic nanomagnets
复制标题
使用超顺磁纳米磁体感测磁场
DOI：
10.1063/1.372938
复制
发表时间：
2000
影响因子：
3.2
通讯作者：
M. Welland
中科院分区：
文献类型：
--
作者：
R. Cowburn;D. Koltsov;A. Adeyeye;M. Welland
利用磁光磁强计研究了电子束光刻制备的超合金纳米磁体的横向尺寸（30 ~ 500 nm）、厚度（3 ~ 7.5 nm）和几何形状（三角形、正方形和五边形）对磁化率和磁滞率的影响。结果表明，随着纳米磁体横向尺寸的减小，磁性柔软度先减小后突然增大。我们表明，这种柔软度的增加是由于热波动克服了纳米磁体几何形状施加的各向异性，导致超顺磁性。因此，可以制造出高磁化率、零磁滞、饱和场为几阶的纳米级磁性元件。讨论了对现场传感技术的启示。
An experimental investigation using magnetooptical magnetometry is described into the dependence of susceptibility and hysteresis on the lateral size (30–500 nm), thickness (3–7.5 nm), and geometric shape (triangular, square, and pentagonal) of supermalloy nanomagnets made by electron beam lithography. We show that as the lateral size of the nanomagnets is reduced, magnetic softness is at first reduced and then increases abruptly. We show that this increase in softness is due to thermal fluctuations overcoming the anisotropy imposed by the geometric shape of the nanomagnets, leading to superparamagnetism. Nanometer scale magnetic elements with high susceptibility, zero hysteresis, and saturation fields of a few oersteds can thus be made. Implications for field sensing technology are discussed.