近日，印度科学研究所的Anindya Das及其研究团队取得一项新进展。经过不懈努力，他们发现双层石墨烯中ν=0量子霍尔铁磁体无热流。相关研究成果已于2024年10月29日在国际知名学术期刊《自然—物理学》上发表。

本实验表明，双层石墨烯中ν=0态的体热传输消失不见，这与理论预测的ν=0态应具有有限热导率相悖。通过改变外部电场并进行温度依赖性测量，这项研究结果表明ν=0态中存在带隙的集体激发。这一发现强调了进一步探究ν=0态性质的必要性。

据悉，双层石墨烯的电荷中性点，即ν=0态，在外加磁场和电场作用下表现出自旋、谷和层自由度自发有序排列的竞争相。然而，由于这些相具有电绝缘性，通过电导测量来识别它们具有挑战性。最近的一项理论建议指出，可以通过热传输测量来检测这些竞争相。

附：英文原文

Title: Absence of heat flow in ν=0 quantum Hall ferromagnet in bilayer graphene

Author: Kumar, Ravi, Srivastav, Saurabh Kumar, Roy, Ujjal, Singhal, Ujjawal, Watanabe, K., Taniguchi, T., Singh, Vibhor, Roulleau, P., Das, Anindya

Issue&Volume: 2024-10-29

Abstract: The charge neutrality point of bilayer graphene, denoted as the ν=0 state, manifests competing phases marked by spontaneous ordering of the spin, valley and layer degrees of freedom under external magnetic and electric fields. However, due to their electrically insulating nature, identifying these phases through electrical conductance measurements is a challenge. A recent theoretical proposal suggests that thermal transport measurements can detect these competing phases. Here we experimentally show that the bulk thermal transport of the ν=0 state in bilayer graphene vanishes. This is in contrast to the theory, which predicts a finite thermal conductance in the ν=0 state. By varying the external electric field and conducting temperature-dependent measurements, our results suggest that there are gapped collective excitations in the ν=0 state. Our findings underscore the necessity for further investigations into the nature of the ν=0 state.

DOI: 10.1038/s41567-024-02673-z

Source: https://www.nature.com/articles/s41567-024-02673-z