Magnetic anisotropy in ancient pottery
Magnetic anisotropy in ancient pottery
复制标题
古代陶器的磁各向异性
作者：
J. Rogers;J. M. W. Fox;M. Aitken
在测量古陶器的热重磁性（TRM）以确定烧制时的场强度时，通过使用Thellier热重磁化技术的修改1，我们观察到，获得TRM的容易程度取决于施加重磁场的角度。一般来说，最硬的方向似乎是垂直于陶器平面的，粗略地说，在陶器平面上有一个“易平面”。这种效应明显不同于与样品形状有关的退磁场的效应，因为对于样品形状观察到各向异性效应，对于样品形状，退磁场不随外加磁场角度的变化而变化（例如在垂直于圆柱体轴线的平面中以各种方位角磁化的圆柱体样品），以及对于比磁化强度太弱以致于去磁场不显著的样品。在交变磁场（750 Hz）测量瞬时磁化率时也观察到了各向异性效应。
WHILST measuring the thermoremanent magnetism (TRM) of ancient pottery to determine the field magnitude at the time of firing, by using a modification of the Thellier thermal remagnetisation technique1, we have observed that the ease with which TRM is acquired is dependent on the angle at which the remagnetising field is applied. As a general rule it seems that the hardest direction is perpendicular to the plane of the pottery and that to a rough approximation there is an ‘easy plane’ lying in the plane of the pottery. The effect is apparently distinct from that due to the demagnetising field associated with sample shape, because the anisotropy effect is observed for sample shapes for which there would be no variation of demagnetising field with change of angle of applied field (such as a cylindrical sample being magnetised at various azimuthal angles in the plane perpendicular to the axis of the cylinder), as well as for samples for which the specific magnetisation is too weak for demagnetising fields to be significant. The anisotropy effect has been observed also in alternating field (750 Hz) measurement of instantaneous susceptibility.