# Generation and detection of pure valley current by electrically induced Berry curvature in bilayer graphene

**Authors:** Yuya Shimazaki, Michihisa Yamamoto, Ivan V. Borzenets, Kenji Watanabe, Takashi Taniguchi, Seigo Tarucha  
**arXiv:** [1501.04776](https://arxiv.org/abs/1501.04776)  
**Date:** 2015-01-20  
**Summary page:** https://www.summarizepaper.com/en/paper/1501.04776v1/

## Key points

- Valley is a property of materials that allows for the flow of current even in insulating materials
- Valley degree of freedom can be utilized in non-dissipative electronics
- Dual-gated bilayer graphene was used to control broken inversion symmetry and carrier density
- Large nonlocal resistance and cubic scaling relationship observed in insulating regime at zero-magnetic field and 70 K
- Ability to electrically control valley current even in materials with zero conductivity
- Non-dissipative induction of valley current achieved solely through an electric field
- Potential for harnessing valley as a degree of freedom in electronics for practical applications
- Findings contribute to understanding non-dissipative electronics and pave the way for further advancements.

## Summary

In the field of electronics, valley is a term used to describe a specific property of materials that allows for the flow of current even in insulating materials. This property is particularly useful for non-dissipative electronics, where electronic current can be generated and detected without any accompanying energy loss. In a recent study, researchers focused on utilizing this valley degree of freedom by using dual-gated bilayer graphene in the Hall bar geometry. The team aimed to electrically control broken inversion symmetry or Berry curvature, as well as the carrier density, in order to generate and detect pure valley current. To investigate this phenomenon, they observed a large nonlocal resistance and identified a cubic scaling relationship between the nonlocal resistance and the local resistivity in the insulating regime at zero-magnetic field and 70 K. These findings provided evidence for the existence of pure valley current. One significant aspect of this research is the ability to electrically control valley current even in materials with zero conductivity. This means that non-dissipative induction of valley current can be achieved solely through an electric field, which has important implications for advancing non-dissipative electronics. Overall, this study highlights the potential for harnessing valley as a degree of freedom in electronics and demonstrates how it can be controlled and utilized for practical applications. The findings contribute to our understanding of non-dissipative electronics and pave the way for further advancements in this field.