Twist-stacked 2D bilayer Fe₃GeTe₂ with tunable magnetism

Abstract

Controlling magnetism in two-dimensional (2D) magnetic compounds is of great significance for potential applications in novel spintronic devices. Based on the van der Waals monolayer, twist-stacking of bilayers can lead...

Li-ion intercalation-driven control of two-dimensional magnetism in van der Waals FePS3 bilayers

“…From the DOS results, we found that the significant enhancement of the Fe-3d and S-3p hybridizations, as well as the reduced Fe–Fe distance, Li–Fe, Li–S, and Li–P bond lengths induced by the location of intercalated Li ions (in the interlayer vdW region), may the reason for the increase in MAE. 2…”

“…48 Consequently, the spin-orbit coupling (SOC) effect, as well as its related exchange interaction, cannot be ignored and has been considered in our calculations. 2,3 The MAE of the three FPS bilayers is defined below as MAE = E 001 À E 100 or E 001 À E 010 , where E 100 , E 010 , and E 001 represent the total energies with an easy axis along the x-, y-and z-axes, respectively. We take the higher value of E 001 À E 100 and E 001 À E 010 as the value of MAE.…”

“…From the DOS results, we found that the significant enhancement of the Fe-3d and S-3p hybridizations, as well as the reduced Fe-Fe distance, Li-Fe, Li-S, and Li-P bond lengths induced by the location of intercalated Li ions (in the interlayer vdW region), may the reason for the increase in MAE. 2 Irrespective of whether Heisenberg, XY, or Ising Hamiltonians, 59 the Ne ´el temperature (T N ) and Curie temperature (T Y ) of the XPS 3 (X = Mn, Fe) materials can be determined by eqn (10) through the mean-field theory 59,64,65 T Y = 4(3J 1 + 6J 2 + 3J 3 )/k B ; T N = 4(J 1 À 2J 2 À 3J 3 )/k B , (10) where k B represents the Boltzmann constant. The calculated results, T N = 110 K for the FePS 3 bilayer, T N = 118 K for 1Li-FPS, and T Y = 220 K for 2Li-FPS, show good agreement with the experimental data (T N = 123 K for 3D bulk FePS 3 ).…”

“…This potential arises from their layered structures, large specific surface areas, low-power requirements, high-switching speeds, ease of exfoliation, and the capacity to enable nonvolatile control of magnetism. 1,2 The vdW gap effectively hinders super-exchange paths between adjacent monolayers, resulting in an ideal two-dimensional (2D) magnetism. Recent breakthroughs in vdW materials, such as ultra-compactness, precise interface controllability, and a wide selection of materials, have facilitated the fabrication of 2D heterostructures and thin films with significant technical importance that cannot be achieved by conventional threedimensional (3D) materials.…”

Small twist, big miracle—recent progress in the fabrication of twisted 2D materials

“…157 Afterwards, a similar situation was also observed in the twisted bilayer InSe, 158 in which the bandwidth can be suppressed to be less than 10 meV at θ = 9.43°. Recently, Chen et al proved that the two Fe 3 GeTe 2 layers can implement an antiferromagnetic–ferromagnetic phase transition by constructing an interlayer rotation, 159 providing a feasible method to tune the interlayer magnetic ordering of 2D compounds. These theoretical research studies adequately demonstrate that twist angle has a strong correlation with the magnetic, electrical and even optical properties of the materials.…”