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Published on: July 24, 2015
Magnetic field tuning of an excitonic insulator between the weak and strong coupling regimes in quantum limit
Z Zhu1,2, R D McDonald3, A Shekhter3,4
1MS-E536, NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA. zengwei.zhu@hust.edu.cn.
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.
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