Magnetic field tuning of an excitonic insulator between the weak and strong coupling regimes in quantum limit graphite.

ABSTRACT: The excitonic insulator phase has long been predicted to form in proximity to a band gap opening in the underlying band structure. The character of the pairing is conjectured to crossover from weak (BCS-like) to strong coupling (BEC-like) as the underlying band structure is tuned from the metallic to the insulating side of the gap opening. Here we report the high-magnetic field phase diagram of graphite to exhibit just such a crossover. By way of comprehensive angle-resolved magnetoresistance measurements, we demonstrate that the underlying band gap opening occurs inside the magnetic field-induced phase, paving the way for a systematic study of the BCS-BEC-like crossover by means of conventional condensed matter probes.

SUBMITTER: Zhu Z 

PROVIDER: S-EPMC5431932 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature