The separation of rare earth (RE) elements is a challenge from their discovery to the present day, due to the chemical and physical similarities as a group. The intrinsic properties of REs are basic for separation mechanisms. Due to the large difference in magnetic moment, a new method of selected crystallization enhanced by magnetic field was developed to separate REs efficiently, at room temperature and pressure without complex equipment. An experimental proof of concept is provided for the binary systems RE 2 (SO 4 ) 3 -Lu 2 (SO 4 ) 3 (RE = Gd, Nd, Tb, Dy or Ho). This magnetic separation process increases the separation factors of Gd(III)/Lu(III) from their mixture by 39% in kinetics, but similar in or near thermodynamic equilibrium without magnetic field. The β RE/Lu (RE = Gd, Nd, Tb, Dy or Ho) were promoted by 17%-47% with permanent magnet, increasing with raising of the applied magnetic field strength. A process based on magnetic moment difference is a potential alternative method for rare-earth separations, with low energy consumption and high efficiency in the presence of an external magnetic field.
Exotic quantum phenomena have been demonstrated in recently discovered intrinsic magnetic topological insulator MnBi2Te4. At its two-dimensional limit, the quantum anomalous Hall effect and axion insulator state were observed in odd and even layers of MnBi2Te4, respectively. Here, we employ low-temperature scanning tunneling microscopy to study the electronic properties of MnBi2Te4. The quasiparticle interference patterns indicate that the electronic structures on the topmost layer of MnBi2Te4 are different from those of the expected out-of-plane A-type antiferromagnetic phase. The topological surface states may be embedded in deeper layers beneath the topmost surface. Such novel electronic structure is presumably related to the modification of crystalline structure during sample cleaving and reorientation of the magnetic moment of Mn atoms near the surface. Mn dopants substituted at the Bi site on the second atomic layer are observed. The electronic structures fluctuate at atomic scale on the surface, which can affect the magnetism of MnBi2Te4.
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