All‐Silicon Switchable Magnetoelectric Effect through Interlayer Exchange Coupling

Abstract

The magnetoelectric (ME) effect originating from the effective coupling between electric field and magnetism is an exciting frontier in nanoscale science such as magnetic tunneling junction (MTJ), ferroelectric/piezoelectric heterojunctions etc. The realization of switchable ME effect under external electric field in d0 semiconducting materials of single composition is needed especially for all-silicon spintronics applications because of its natural compatibility with current industry. We employ density functional theory (DFT) to reveal that the pristine Si(111)-3×3 R30° (Si3 hereafter) reconstructed surfaces of thin films with a thickness smaller than eleven bilayers support a sizeable linear ME effect with switchable direction of magnetic moment under external electric field. This is achieved through the interlayer exchange coupling effect in the antiferromagnetic regime, where the spin-up and spin-down magnetized density is located on opposite surfaces of Si3 thin films. The obtained coefficient for the linear ME effect can be four times larger than that of ferromagnetic Fe films, which fail to have the reversal switching capabilities. The larger ME effect originates from the spin-dependent screening of the spin-polarized Dirac fermion. The prediction will promote the realization of well-controlled and switchable data storage in all-silicon electronics.

Screening Magnetic Two-Dimensional Atomic Crystals with Nontrivial Electronic Topology

“…To date 2D magnetic materials are limited to marginal modifications to existing compounds, for instance by: (i) adsorbing hydrogen on graphene 23 ; (ii) reconstructing surface/edge [24][25] ; or (iii) creating defects in MoS 2 nanosheets 26 . The intrinsic 2D ferromagnetism has only been observed in atomically thin CrI 3 and CrGeTe 3 , only accessible at a low temperature of ~40 K [27][28] .…”

“…30 mK for Cr-doped (Bi,Sb) 2 Te 3 thin film) [16][17][18][19][20][21][22] , hampering its extensive applications. Therefore, discovery of 2D magnets at an elevated temperature is of great importance, providing optimal platforms to enable realistic spintronic and quantum devices, as well as to realize new electronic states.To date 2D magnetic materials are limited to marginal modifications to existing compounds, for instance by: (i) adsorbing hydrogen on graphene 23 ; (ii) reconstructing surface/edge [24][25] ; or (iii) creating defects in MoS 2 nanosheets 26 . The intrinsic 2D ferromagnetism has only been observed in atomically thin CrI 3 and CrGeTe 3 , only accessible at a low temperature of ~40 K 27-28 .…”

“…The Mermin–Wagner theorem shows that the 2D isotropic Heisenberg model prohibits the occurrence of 2D magnetic order, while this restriction is removed by magnetic anisotropy, possibly leading to 2D Ising magnetism . To date, 2D magnetic materials are limited to marginal modifications to existing compounds, for instance by (i) adsorbing hydrogen on graphene, (ii) reconstructing surface/edge, , or (iii) creating defects in MoS 2 nanosheets . The intrinsic 2D ferromagnetism has only been observed in atomically thin CrI 3 and CrGeTe 3 , only accessible at a low temperature of ∼40 K. , The absence of ideal 2D magnetic materials indicates that traditional trial-and-error approaches to discover new materials are not effective.…”