Two-dimensional triangular-lattice antiferromagnets are predicted under some conditions to exhibit a quantum spin liquid ground state with no energy barrier to create emergent, fractionalized spinon excitations that carry spin but no charge. Materials that realize this kind of spin liquid are expected to have a low-energy behaviour described by a spinon Fermi surface. Directly imaging the resulting spinons, however, is difficult due to their chargeless nature. Here we use scanning tunnelling spectroscopy to image density waves consistent with the predictions of spinon density modulation arising from a spinon Fermi surface instability in single-layer 1T-TaSe₂. We confirm the existence of a triangular lattice of localized spins in this material by contacting it with a metallic 1H-TaSe₂ substrate and measuring the Kondo effect. Spectroscopic imaging of isolated single-layer 1T-TaSe₂ reveals long-wavelength super-modulations at Hubbard band energies, consistent with the predicted behaviour of itinerant spinons. These super-modulations allow the direct experimental measurement of the spinon Fermi wavevector, in good agreement with theoretical predictions for a two-dimensional quantum spin liquid.

预测二维三角晶格反铁磁体在某些条件下会表现出量子自旋液态基态，没有能垒，以产生带有自旋但不带电荷的涌现、分级自旋激发。实现这种自旋液体的材料预计将具有由自旋费米表面描述的低能行为。然而，由于它们不带电的性质，直接成像产生的旋子是很困难的。在这里，我们使用扫描隧道光谱对密度波进行成像，这与由单层 1T-TaSe ₂中的旋子费米表面不稳定性引起的旋子密度调制的预测一致。_{我们通过将其与金属 1H-TaSe 2}接触来确认该材料中存在局部自旋的三角形晶格基板和测量近藤效应。孤立的单层 1T-TaSe ₂的光谱成像揭示了哈伯德波段能量的长波长超调制，这与流动旋子的预测行为一致。这些超调制允许对旋子费米波矢量进行直接实验测量，这与二维量子自旋液体的理论预测非常吻合。