We report in situ generation of a 6,6′-biindeno [1,2-b]anthracene (BIA) derivative as an open-shell biaryl with high diradical character, which could be identified by mass spectrometry, NMR spectroscopy, single-crystal X-ray analysis, UV−vis−NIR absorption spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. Theoretical calculations by various methods and variable-temperature EPR analyses were performed to tackle the elusive ground state of BIA diradical, suggesting a singlet ground state with a nearly degenerate triplet state. These results provide insight into the design of unique open-shell biaryls.

Cr 1+δ Te 2 is a self-intercalated transition metal dichalcogenide that hosts tunable electronic filling and magnetism in its semimetallic band structure. Recent angle-resolved photoemission spectroscopy (ARPES) studies have unveiled a systematic shift in this semimetallic band structure relative to the chemical potential with increased Cr doping. This paper presents the temperature and magnetic field dependence of the longitudinal thermopower S xx for different Cr 1+δ Te 2 compositions. We show that as doping increases, the sign of S xx changes from positive to negative at the critical doping level of δ ∼ 0.5. This observed doping-dependent trend in the thermopower is consistent with the evolution of the semimetallic band structure from ARPES. Importantly, an anomalous enhancement of the thermoelectric response near T C is also observed around δ ∼ 0.5. Combining information from magnetometry and ARPES measurements, existence of the critical nature of the doping level δ c (∼ 0.5) is unveiled in magnetic semimetal Cr 1+δ Te 2 , where antiferromagnetic fluctuation and near-Fermienergy pseudogap formation play a potential vital role in enhancing thermoelectric energy conversion.

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