近日，复旦大学沈健团队研究了巨非线性谷霍尔效应的观测。这一研究成果发表在2026年3月31日出版的《自然—物理学》杂志上。

谷电子学应用利用谷自由度——即状态波函数在布里渊区中的位置——来存储和处理信息。在这一背景下，谷霍尔效应对读取和写入谷态至关重要。迄今为止，关于该效应的研究都集中在其对外加电流的线性响应上，尚未考虑非线性响应。

研究组报道了在石墨烯莫尔超晶格中观测到的非线性谷霍尔效应，其表现为在交流电流驱动下产生二次谐波非局域电压。观测到的非线性效应幅度超过了线性版本，并且可通过栅极电压进行高度调控。非线性信号与驱动电流呈二次方标度关系，与局域电阻呈四次方标度关系，这使其区别于线性效应。研究组进一步通过观测三次和四次谐波非局域电压，揭示了非线性逆谷霍尔效应。该效应为谷操控提供了一种机制，并可能实现一种能将交流电荷电流转换为直流谷电流的谷整流器件。

附：英文原文

Title: Observation of giant nonlinear valley Hall effect

Author: He, Pan, Zhang, Min, Cao, Jin, Li, Jingru, Liu, Hao, Zhai, Jinfeng, Wang, Ruibo, Xiao, Cong, Yang, Shengyuan A., Shen, Jian

Issue&Volume: 2026-03-31

Abstract: Valleytronic applications utilize the valley degree of freedom—that is, the location of a state’s wavefunction within the Brillouin zone—to store and process information. In this context, the valley Hall effect is important for reading and writing the valley state. So far, research on this effect has focused on its linear response to an applied current and has not considered nonlinear responses. Here we report the observation of a nonlinear valley Hall effect in a graphene moiré superlattice, indicated by the generation of second-harmonic non-local voltages under a.c. currents. The nonlinear effect we observe has a magnitude surpassing the linear version and is highly tunable with a gate voltage. The nonlinear signal shows quadratic scaling with driving current and quartic scaling with local resistance, setting it apart from its linear counterpart. We further reveal a nonlinear inverse valley Hall effect by observing the third- and fourth-harmonic non-local voltages. This effect provides a mechanism for valley manipulation and may enable a valley rectifier device that converts a.c. charge current into d.c. valley current.

DOI: 10.1038/s41567-026-03221-7

Source: https://www.nature.com/articles/s41567-026-03221-7