Yang Yu
U-M Physics

Magnetic Phases of the Anisotropic Triangular Lattice Hubbard Model

The Hubbard model on an anisotropic triangular lattice in two dimensions, a fundamental model for frustrated electron physics, displays a wide variety of phases and phase transitions. This work investigates the model using the ladder dual fermion approximation which captures local correlations non-perturbatively but approximates non-local correlations. We find metallic, one-dimensional antiferromagnetic, non-collinear antiferromagnetic, square-lattice antiferromagnetic, and spiral phases but no evidence of collinear antiferromagnetic order in different parts of the phase diagram. Analyzing the spin susceptibility in detail, we see both regions of agreement and of discrepancy with previous work. The case of Cs2CuCl4 is discussed in detail.

Reference:
https://arxiv.org/abs/2211.09234.


Torben Purz
MONSTR Sense Technologies

Coherent Imaging Spectroscopy of Transition Metal Dichalcogenides

Transition Metal Dichalcogenides (TMDs) monolayers and heterostructures are a promising material platform for quantum information science, photovoltaics, and related device applications. In the past decade, much effort has been dedicated to explore the exciton physics in these materials, ranging from their strong light-matter coupling to charge transfer and coherent coupling. However, many demonstrations in TMDs can only be realized at specific spots on the sample, presenting a challenge to the scalability of these applications.

In this talk, I will demonstrate Multi-Dimensional Coherent Imaging Spectroscopy of TMDs and highlight the sensitivity of exciton spatial and temporal coherence toward strain while coherent exciton coupling and charge transfer in these samples remain mostly unaffected, strengthening the case for TMDs as next-generation material platform in quantum information science and beyond. In addition, I will demonstrate rapid nonlinear imaging spectroscopy of TMDs that assesses the quality of samples through measurement of their nonlinear response, exciton dephasing, exciton lifetimes, and exciton-coupling strength. By comparison, I will show that extracting material parameters such as four-wave mixing intensity, dephasing times, excited state lifetimes, exciton-coupling strength, and distribution of dark/localized states allows for a more accurate assessment of the quality of a sample than current prevalent techniques, including white light microscopy, linear micro-reflectance spectroscopy, and photo-luminescence.