Roadmap on finding chiral valleys: screening 2D materials for valleytronics

Abstract

In this review, we present an update on the methods for screening 2D materials suitable for valleytronic applications. We begin with an introduction to the field highlighting some of the latest findings and seminal works. Then we provide a brief background on the physics of valley- and layer- pseudospins in layered 2D materials such as transition metal dichalcogenides. This is followed by a detailed survey of a number of key techniques commonly employed to elucidate valley properties in such materials, highlighting in particular their capability for discriminating valley pseudospins, their key advantages and current limitations. Finally, we conclude by summarising the state-of-the-art assessing materials for valleytronic applications and point the reader to the current open questions that could have critical influence on the technological impact that may be derived from such materials.

Proximity exchange effects in MoSe2 and WSe2 heterostructures with CrI3 : Twist angle, layer, and gate dependence

“…3(a) we show the calculated band structure of 2H bilayer MoSe 2 on top of monolayer CrI 3 without considering SOC effects. The bilayer TMDC has an indirect band gap, consistent with literature 83,84 . For the CB edge, see Fig.…”

Toward Valley‐Coupled Spin Qubits

“…The lack of an in‐plane inversion center, implies that the single‐layer TMDCs intrinsically host inequivalent valleys at the K and points of their hexagonal Brillouin Zone. [ 27 ] In addition, the large spin–orbit coupling carried by the transition atoms combined with the time reversal symmetry, introduces an energy splitting of opposite signs at the K and valleys, leading to a coupling of opposite spins to the K and valleys. This unique “spin‐locking” mechanism makes the valleys addressable via their incumbent spins and primes the single‐layer TMDCs for spintronic and valleytronic applications, where the spin and valley degrees of freedom are explored for accelerating electronic computing and information processing.…”

“…This unique “spin‐locking” mechanism makes the valleys addressable via their incumbent spins and primes the single‐layer TMDCs for spintronic and valleytronic applications, where the spin and valley degrees of freedom are explored for accelerating electronic computing and information processing. [ 27 ]…”

“…[ 22,23,26 ] Significantly, the inherent inversion asymmetry in such TMDCs results in a unique spin‐valley coupling which is expected to enhance the coherence lifetime of spin‐valley states thus making the TMDC platform advantageous for robust qubits. [ 22,23,27 ] The single‐layer TMDCs are readily transferrable [ 28 ] to a Si wafer or may be grown [ 29 ] directly onto a Si wafer, and the majority of TMDC‐based devices have been fabricated on the Si wafer. [ 30,31 ] Significant research efforts are also underway to develop strategies for compatibility with Si CMOS technologies.…”

“…Snapshots of the key facilities available at A*STAR (Singapore) for the growth and characterization of transition metal dichalcogenides (TMDC) materials. [ 27,83 ] a) The system shown is a 3 zone furnace for growing high quality TMDC layer by chemical vapor deposition (CVD) technique. The quality of as‐grown TMDC materials can be typically assessed by optical microscopy and Raman spectroscopy, but the b) circular dichroic photoluminescence spectroscopy (CDPL) setup allows a rapid, noninvasive screening of valley polarization in 2D materials.…”