1t-tase Quantum Spin Liquid Candidate Exhibits Low-Energy Excitations Via Inelastic Tunneling Spectroscopy

The search for quantum spin liquids, exotic states of matter exhibiting collective behaviour and fractional excitations, faces a significant challenge when applied to two-dimensional materials, as existing experimental techniques lack the necessary sensitivity. Ziying Wang, Adolfo O. Fumega, and Ana Vera Montoto, alongside colleagues at Aalto University, now present compelling evidence for a modulated spin liquid state in the material 1T-TaSe, overcoming this limitation. The team employs a technique called inelastic tunneling spectroscopy to directly measure low-energy excitations within the material, revealing a reconstruction driven by the substrate and a unique coexistence of zero and finite energy excitations. These observations demonstrate that this method provides a powerful new way to investigate the magnetic properties of two-dimensional materials at the atomic scale, and opens up exciting possibilities for understanding the influence of moiré modulations on potential quantum spin liquid phases.

Probing these states experimentally presents a significant challenge, particularly in two-dimensional materials. Researchers now investigate 1T-TaSe2 as a promising candidate, focusing on how subtle structural changes influence its quantum properties. This work contributes to a broader understanding of quantum materials and the pursuit of realising and characterising these fascinating phases of matter.

Materials such as 1T-TaSe2 are actively researched as potential quantum spin liquid candidates. Scanning tunneling microscopy and spectroscopy recently emerged as powerful tools to investigate these states, allowing scientists to directly measure the energy of spinons through inelastic electron tunneling spectroscopy. This work applies this approach to 1T-TaSe2, directly measuring its low-energy excitations. Observations reveal a reconstructed structure, consistent spectroscopic signals across all spin sites, and the coexistence of both zero and finite energy excitations, supporting a modulated spin liquid ground state.
D Materials Exhibit Quantum Phenomena

This research centres on investigating the electronic and magnetic properties of two-dimensional materials, with a particular focus on 1T-TaSe2. This material exhibits strong interactions between electrons and complex electronic behaviour, making it a promising platform for exploring quantum phenomena. Scientists are also investigating van der Waals heterostructures, created by combining different 2D materials to create novel properties. The primary experimental technique employed is scanning tunneling microscopy and spectroscopy, which allows scientists to image materials at the atomic scale and probe their electronic structure, identifying features such as the local density of states, energy gaps, and spin-flip excitations.

Researchers also utilise inelastic electron tunneling spectroscopy to investigate vibrational modes and their influence on electronic properties. On-surface synthesis techniques are used to create novel structures and materials directly on a surface, enabling the fabrication of van der Waals heterostructures. The research reveals a complex electronic structure in 1T-TaSe2, characterised by strong electron correlations and charge density waves. Kondo resonances are observed, indicating the presence of localised magnetic moments, and Yu-Shiba-Rusinov states, bound states formed due to the interaction of magnetic impurities with the material’s surface states, are also identified.

Evidence of spin-flip excitations provides insights into the magnetic properties of the materials, while vibrational modes are identified using inelastic electron tunneling spectroscopy. Moiré patterns, arising from the interaction between the material and its substrate, are observed and found to influence the electronic and magnetic properties. This research has the potential to advance our understanding of quantum materials and provide deeper insights into the behaviour of strongly correlated 2D materials. It could lay the groundwork for creating novel quantum devices, such as quantum sensors and spintronic devices, and the investigation of quantum spin liquids could lead to new applications in quantum computing.

Moiré Modulation Reveals Spin Liquid Ground State

This research demonstrates a new approach to understanding quantum spin liquid materials, specifically the compound 1T-TaSe2. Scientists successfully used scanning tunneling microscopy and spectroscopy to directly measure the low-energy excitations within this material. The team observed a reconstructed structure, consistent spectroscopic signals across all spin sites, and a combination of zero and finite energy excitations, supporting the existence of a modulated spin liquid ground state. The findings reveal that moiré modulation, a periodic pattern arising from the interaction between the material and its substrate, plays a crucial role in shaping the material’s low-energy excitations. Both theoretical modelling and experimental data indicate that this modulation significantly influences the observed excitation spectrum, establishing a strategy for exploring quantum spin liquid phases using scanning tunneling microscopy techniques. Researchers acknowledge that the specific substrate used for sample growth introduces the moiré modulation, and future research could investigate the impact of different substrates or explore methods to control and manipulate these modulations.