Interlayer electronic coupling on demand in a 2D magnetic semiconductor

Abstract

When monolayers of two-dimensional (2D) materials are stacked into van der Waals structures, interlayer electronic coupling can introduce entirely new properties, as exemplified by recent discoveries of moiré bands that host highly correlated electronic states and quantum dot-like interlayer exciton lattices. Here we show the magnetic control of interlayer electronic coupling, as manifested in tunable excitonic transitions, in an A-type

Quasi 1D electronic transport in a 2D magnetic semiconductor

“…Scanning tunneling spectroscopy measurements have shown that the Fermi level is very close to the bottom of -or possibly inside-the conduction band and that charge carriers are electrons [23], but their microscopic origin (i.e., what is the doping mechanism) and precise density are currently unknown. Rather uncommonly, the relatively large low-temperature conductivity -which confirms the presence of sizable non-intentional doping-coexists with a bright fluorescence observed in photoluminescence experiments (see Figure 1e) [24]. Additionally, the same band structure calculations (see Figure 1b) predicting a large bandwidth also show an extremely pronounced anisotropy: the bandwidth is about 1.5 eV in the Γ − Y (which corresponds to the crystallographic b-axis), but nearly vanishes in the perpendicular Γ − X direction (i.e., in the a-direction) [24,25].…”

“…Rather uncommonly, the relatively large low-temperature conductivity -which confirms the presence of sizable non-intentional doping-coexists with a bright fluorescence observed in photoluminescence experiments (see Figure 1e) [24]. Additionally, the same band structure calculations (see Figure 1b) predicting a large bandwidth also show an extremely pronounced anisotropy: the bandwidth is about 1.5 eV in the Γ − Y (which corresponds to the crystallographic b-axis), but nearly vanishes in the perpendicular Γ − X direction (i.e., in the a-direction) [24,25]. Even though this prediction is somewhat surprising, because no obvious pronounced anisotropy can be identified in the atomic structure of the material (see Figure 1a), indications of anisotropy (see Figure 1e) were indeed found when measuring the photoluminescence polar- ization dependence [24].…”

“…Such narrow bandwidths cause electron localization and prevent low-temperature conductivity measurements, which is why transport experiments probing the magnetic properties of 2D semiconductors have been so far limited to studies of tunneling through atomically thin multilayer barriers [14][15][16][17][18][19][20][21]. CrSBr [22] (see Figure 1a) -a recently introduced 2D magnetic semiconductorappears to be an exception [23,24]. First-principles calculations (shown in Figure 1b) predict its conduction band to have a width of approximately 1.5 eV [24,25].…”

“…CrSBr [22] (see Figure 1a) -a recently introduced 2D magnetic semiconductorappears to be an exception [23,24]. First-principles calculations (shown in Figure 1b) predict its conduction band to have a width of approximately 1.5 eV [24,25]. Accordingly, low-temperature in-plane magnetoresistance measurements (see Figure 1c and d) could be performed successfully, and analyzed to determine the magnetic phase diagram [23].…”

Triaxial magnetic anisotropy in the two-dimensional ferromagnetic semiconductor CrSBr

“…The FM ordering is remarkably retained in CrI 3 monolayer with the Curie temperature (T C ) ∼ 45 K and in Cr 2 Ge 2 Te 6 bilayer with T C ∼ 30 K under a tiny magnetic field. These discoveries stimulate extensive research on the emergent magnetism in the 2D limit and its promising technological applications in spintronics [3][4][5][6][7][8][9][10][11]. As the 2D isotropic Heisenberg spin systems have no long-range magnetic order at finite temperature according to the Mermin-Wagner theorem [12], magnetic anisotropy (MA) is indispensable for stabilizing the 2D magnetic order.…”