0.5%アルミニウム鉄の単結晶及び多結晶の初帯磁率とそれに対する消磁方法の影響

Abstract

The initial magnetic susceptibility, χ0, has been studied at ordinary temperatures, using the ballistic method, with single crystal and polycrystal rods of iron containing 0.53%Al in thermally demagnetized (TD) state and in alternating-current demagnetized (AD) state. The results of measurements and conclusions obtained are as follows: Either in single crystals or in polycrystal, irrespective of crystal orientation, (χ0)TD>(χ0)AD and, regardless of the method of demagnetization, χ0[100]>χ0[110]>χ0[111] and (χ0)poly>(χ0)single. The measured facts concerning the difference in the method of demagnetization may be explained by an idea of small uniaxal ferromagnetic anisotropies with negative and postive anisotropy constants induced, respectively, by TD and AD, and the observed relation between polycrystal and single crystal data may be interpreted in terms of the magnetic interaction between crystal grains. For both of TD and AD states, the observed anisotropy of χ0 accords well with the formula χ0=χ0[100][2(∑\limitsiβi3⁄∑\limitsiβi)−{∑\limitsiβi3⁄(∑\limitsiβi)2}], which is derived from Brown’s theory of domain wall displacements, for the case where the assembly of 180° domains is present and the relative volumes of domains in unmagnetized state are given by vi0=(1⁄2)(βi⁄∑jβj).