近日，美国康奈尔大学Kin Fai Mak团队研究了偶极激子绝缘体中的完美库仑阻力。这一研究成果于2025年4月18日发表在《科学》杂志上。
激子绝缘体（EI）是物质玻色子相的固态原型，可以支持电荷中性激子电流。然而，在EIs中证明激子输运是困难的。在这项工作中，研究组表明，在由2纳米势垒隔开的MoSe2/WSe2双层中，在相等的电子和空穴密度下，强烈的层间激子相关性在零磁场下产生了完美的库仑阻力：在低温下，一层中的电荷电流在另一层中感应出相等但相反的阻力电流。
阻力流比保持在0.9以上，最高可达约20开尔文。当激子密度增加到莫特密度以上时，激子突然离解成电子空穴等离子体，只观察到摩擦阻力。该实验可能会导致激子电路和超流体的实现。
附：英文原文
Title: Perfect Coulomb drag in a dipolar excitonic insulator
Author: Phuong X. Nguyen, Liguo Ma, Raghav Chaturvedi, Kenji Watanabe, Takashi Taniguchi, Jie Shan, Kin Fai Mak
Issue&Volume: 2025-04-18
Abstract: Excitonic insulators (EIs) are a solid-state prototype for bosonic phases of matter that can support charge-neutral exciton currents. However, demonstration of exciton transport in EIs is difficult. In this work, we show that the strong interlayer excitonic correlation at equal electron and hole densities in MoSe2/WSe2 double layers separated by a 2-nanometer barrier yields perfect Coulomb drag under zero magnetic field: A charge current in one layer induces an equal but opposite drag current in the other layer at low temperatures. The drag current ratio remains above 0.9 up to about 20 kelvin. As exciton density increases above the Mott density, the excitons dissociate into an electron-hole plasma abruptly, and only frictional drag is observed. Our experiment may lead to the realization of exciton circuitry and superfluidity.
DOI: adl1829
Source: https://www.science.org/doi/10.1126/science.adl1829