Large magnetocrystalline anisotropy of Fe_3−xCr_xSe₄ single crystals due to Cr substitution

Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences 72 Wenhua Road, Shenyang, 110016, PRC

^(a) dali@imr.ac.cn

Received: 15 October 2014
Accepted: 25 January 2015

Abstract

High-quality single crystals of sheet-like Fe_3−xCr_xSe₄ (x = 0, 0.5, 0.7, 0.9) with preferential orientation have been grown by a high-temperature flux method. First-principles calculations show that the lowest surface formation energy of the (001) crystal plane drives the layer growth. The magnetocrystalline anisotropy of the Fe_3−xCr_xSe₄ crystals has been determined to be uniaxial with the b-axis as easy-magnetization direction. In Fe₃Se₄, a monotonic decrease of the magnetization with increasing temperature is observed, while the magnetization of the Cr-doped Fe_3−xCr_xSe₄ crystals increases upon cooling and then decreases at some temperature, which increases with the Cr content. The Curie temperature , anisotropy field and anisotropy constant at 300 K for Fe_2.5Cr_0.5Se₄ are 365 K, 54.2 kOe and , respectively, much higher than for the undoped Fe₃Se₄. This significant increase in the magnetic parameters T_C, H_K and K_u may be attributed to an enhanced ferromagnetic exchange coupling tuned by suitable Cr substitution in Fe₃Se₄.