Layer-resolved magnetic proximity effect in van der Waals heterostructures

Abstract

Magnetic proximity effects are crucial ingredients for engineering spintronic 1 , superconducting 2 , and topological phenomena 3,4 in heterostructures. Such effects are highly sensitive to the interfacial electronic properties, such as electron wave function overlap and band alignment. The recent emergence of van der Waals (vdW) magnets enables the possibility of tuning proximity effects via designing heterostructures with atomically clean interfaces 5-20 . In particular, atomically thin CrI3 exhibits layered antiferromagnetism, where adjacent ferromagnetic monolayers are antiferromagnetically coupled 5 . Exploiting this magnetic structure, we uncovered a layer-resolved magnetic proximity effect in heterostructures formed by monolayer WSe2 and bi/trilayer CrI3. By controlling the individual layer magnetization in CrI3 with a magnetic field, we found that the spindependent charge transfer between WSe2 and CrI3 is dominated by the interfacial CrI3 layer, while the proximity exchange field is highly sensitive to the layered magnetic structure as a whole. These properties enabled us to use monolayer WSe2 as a spatially sensitive magnetic sensor to map out layered antiferromagnetic domain structures at zero magnetic field as well as antiferromagnetic/ferromagnetic domains near the spin-flip transition in bilayer CrI3. Our work reveals a new way to control proximity effects and probe interfacial magnetic order via vdW engineering 21 . Main Text:At the interface formed by a magnetic and nonmagnetic material, the magnetic order can drastically influence the properties of the nonmagnetic component 22,23 , which can expose new functionalities absent from the individual materials. This proximity effect is usually short-ranged due to the finite extension of the electronic wavefunctions across the interface. Thus, vdW materials, which feature atomic thicknesses and form atomically sharp interfaces, are an attractive platform to realize and harness the proximity effect.

Observation of site-controlled localized charged excitons in CrI3/WSe2 heterostructures

“…The broad spectrum shown in Fig. 1 c is consistent with previous observations 19 , 22 and can be attributed to delocalized X + species. In contrast to this broad spectrum, in the vicinity of the nanopillars, we observe multiple narrow linewidth emission lines.…”

Room temperature near unity spin polarization in 2D Van der Waals heterostructures

“…The generation and control of spin polarization is at the heart of this field. One recent progress along this direction is the light-induced spin and valley polarization in transition metal dichalcogenides (TMDCs) [14][15][16][17] and their heterostructures [18][19][20][21][22] . However, most of these studies were performed at low temperature with highquality samples, so as to reduce the intervalley scattering and increase the spin-valley polarization lifetime 23,24 .…”

Chiral Spin Spirals at the Surface of the van der Waals Ferromagnet Fe3GeTe2

“…These magnetic textures in vdW magnets are still largely unexplored and are currently a topic to which significant research efforts are devoted. 20 − 23 Unveiling these spin structures in two-dimensions can give a significant push towards a deeper understanding of magnetism in lower dimensions, along with the prospect of using vdW magnets for future applications.…”