Emergence of a real-space symmetry axis in the magnetoresistance of the one-dimensional conductor Li<sub>0.9</sub>Mo<sub>6</sub>O<sub>17</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31281877.
- Also identified by DOI 10.1126/sciadv.aar8027 and PMC identifier 6611691.
- Licence recorded as CC BY-NC.
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Abstract
We report on an emerging symmetry axis in the magnetoresistance of bulk single crystals of quasi-one-dimensional Li<sub>0.9</sub>Mo<sub>6</sub>O<sub>17</sub> below <i>T</i> <sub>min</sub> = 25 K, the temperature at which the electrical resistivity experiences a minimum. Detailed angle-dependent magnetoresistance sweeps reveal that this symmetry axis is induced by the development of a negative magnetoresistance, which is suppressed only for magnetic fields oriented along the poles of the MoO<sub>6</sub> octahedra that form the conducting chains. We show that this unusual negative magnetoresistance is consistent with the melting of dark excitons, composed of previously omitted orbitals within the <i>t</i> <sub>2g</sub> manifold that order below <i>T</i> <sub>min</sub>. The unveiled symmetry axis in directional magnetic fields not only provides evidence for the crystallization of these dark excitons but also sheds new light on the long-standing mystery of the metal-insulator transition in Li<sub>0.9</sub>Mo<sub>6</sub>O<sub>17</sub>.