On the Magnetocrystalline Anisotropy of Iron Selenide Fe_7Se_8

概要

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Magnetization measurements along the α- and c-axes of a single crystal of a compound Fe_7Se_8 have been carried out in magnetic fields up to 92 kOe over the temperature range from 4.2° to 300°K, together with magnetic torque measurements on the bc-plane up to 9 kOe. The results of magnetization measurements along the c-axis lead to the magnetocrystalline anisotropy energy of the form, E(θ)=-K_0|cosθ|+K_3 cos^2θ+K_4 cos^4θ, the last term being for minor correction. In this expression θ is an angle between magnetization and field direction. The measured values of anisotropy constants K_0 and K_3 at 290°, 77° and 4.2°K are K_0=0.3×10^6, 32×10^6 and 65×10^6 erg/cc and K_3=2.5×10^6, 18×10^6 and 35×10^6 erg/cc, respectively. From the magnetocrystalline energy mentioned above, it can be shown that the magnetic moment takes a conical distribution around the c-axis at low temperatures. The results of torque measurements on the bc-plane is reproduced by assuming a triad crystal domain structure.
東北大学の論文