Valleytronics in merging Dirac cones: All-electric-controlled valley filter, valve and universal reversible logic gate

TL;DR

This paper introduces all-electric valleytronic devices utilizing merging Dirac cones, enabling efficient valley polarization control, high magnetoresistance ratios, and reversible logic gates, advancing potential applications in information processing and quantum computing.

Contribution

It proposes a novel all-electric valley filter, valve, and universal reversible logic gate based on valley-contrasting transport in merging Dirac cones systems, with practical switching and stability features.

Findings

Achieved over 10,000% valley-pseudo-magnetoresistance ratio.

Demonstrated a valleytronic logic gate covering all 16 Boolean functions.

Revealed valley degree of freedom enables logical reversibility.

Abstract

Despite much anticipation of valleytronics as a candidate to replace the ageing CMOS-based information processing, its progress is severely hindered by the lack of practical ways to manipulate valley polarization all-electrically in an electrostatic setting. Here we propose a class of all-electric-controlled valley filter, valve and logic gate based on the valley-contrasting transport in a merging Dirac cones system. The central mechanism of these devices lies on the pseudospin-assisted quantum tunneling which effectively quenches the transport of one valley when its pseudospin configuration mismatches that of a gate-controlled scattering region. The valley polarization can be abruptly switched into different states and remains stable over semi-infinite gate-voltage windows. Colossal tunneling valley-pseudo-magnetoresistance ratio of over 10,000\% can be achieved in a valley-valve setup. We further propose a valleytronic-based logic gate capable of covering all 16 types of two-input Boolean logics. Remarkably, the valley degree of freedom can be harnessed to resurrect logical-reversibility in two-input universal Boolean gate. The (2+1) polarization states -- two distinct valleys plus a null polarization -- re-establish one-to-one input-to-output mapping, a crucial requirement for logical-reversibility, and significantly reduce the complexity of reversible circuits due to the built-in nature of valley degree of freedom. Our results suggest that the synergy of valleytronics and digital logics may provide new paradigms for valleytronic-based information processing and reversible computing.