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Charge Density Wave Hampers Exciton Condensation in 1 T-TiSe 2
| Content Provider | Semantic Scholar |
|---|---|
| Author | Lian, Chao Zhao, Yinchang Ali, Z. Abdel-Khalek Wong, Bryan M. |
| Copyright Year | 2019 |
| Abstract | The Bose-Einstein condensation of excitons continues to garner immense attention as a prototypical example for observing emergent properties from many-body quantum effects. In particular, Titanium Diselenide (TiSe2) is a promising candidate for realizing exciton condensation and was experimentally observed only very recently [Science 358 1314 (2017)]. Surprisingly, the condensate was experimentally characterized by a soft plasmon mode that only exists near the transition temperature, Tc, of the charge density wave (CDW). Here, we characterize and analyze the experimental spectra using linear-response time-dependent density functional theory and find that the soft mode can be attributed to interband electronic transitions. At the CDW state below Tc, the periodic lattice distortions hamper the spontaneous formation of the exciton by introducing a CDW gap. The band gap raises the soft mode and merges it into the regular plasmon. Our surprising results contradict previous simplistic analytical models commonly used in the scientific literature. In addition, we find that a finite electronic temperature, Te, introduces a dissipation channel and prevents the condensation above Tc. The combined effect of the CDW and Te explains the fragile temperature-dependence of the exciton condensation. Taken together, our work provides the first ab initio atomic-level framework for rationalizing recent experiments and further manipulating exciton condensates in TiSe2. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://arxiv-export-lb.library.cornell.edu/pdf/1901.11223 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
