Large magnetocrystalline anisotropy of Fe3−xCrxSe4 single crystals due to Cr substitution

Abstract

High-quality single crystals of sheet-like Fe3−xCrxSe4 (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 Fe3−xCrxSe4 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 Fe3−xCrxSe4 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 Fe2.5Cr0.5Se4 are 365 K, 54.2 kOe and , respectively, much higher than for the undoped Fe3Se4. This significant increase in the magnetic parameters TC, HK and Ku may be attributed to an enhanced ferromagnetic exchange coupling tuned by suitable Cr substitution in Fe3Se4.