Compound The R <sub> 2 </ Sub> Fe <sub> 14 </ Sub> B (r = Nd Or Ho) Of The Magnetic Anisotropy

In this work, linear theory has been developed. We present modified linear theory for systems of rare-earth-transition-metal (RT) compounds based on newly defined normalized generalized Brillouin functions. The magnetocrystalline anisotropy of R₂Fe₁₄B(R=Nd or Ho) are studied by using the new linear theory.Magnetocrystalline anisotropy is one of characters of the permanent-magnetic material and it depends obviously on temperature. The main advantage of this analytical expression is that the temperature dependence of magnetocrystalline anisotropy is given directly as that of the normalized generalized Brillouin functions with appropriate quantum number J. In this work,the molecular field B_ex depends on the temperature. This temperature dependence isapproximated by B_ex(T) = B_ex(4.2K) .The main results are as follows:1. The dependence of the magnetocrystalline anisotropy energy E_an on θ (the anglebetween magnetization direction and the c axis) for R₂Fe₁₄B(R=Nd or Ho) is obtained at 4.2 K using new linear theory.2. The temperature dependence of the cone angle can be found. In compounds with Nd³⁺ and Ho³⁺, the magnetization vectors at 4.2 K are tilted from the c axis atabout 30.4° and 22.4°, respectively. The cone angles of the two compounds decreasemonotonically with increasing temperature, and reach zero at 133.5 K and 58.1 K, respectively.3. The temperature dependence of magnetocrystalline anisotropy constants are given within the normalized generalized Brillouin functions.Our results in R₂Fe₁₄B (R=Nd or Ho) compounds are in good agreement with previously experimental data. The model provides a physically transparent picture. It is expected that linear theory will be extensive valuable in interpreting various magnetic measurements in similar hard magnets.