Tunable breakdown of the polaron picture for mobile impurities in a topological semimetal
| Autor: | Caracanhas, M. A., Pereira, R. G. |
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| Rok vydání: | 2016 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 94, 220302 (2016) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.94.220302 |
| Popis: | Mobile impurities in cold atomic gases constitute a new platform for investigating polaron physics. Here we show that when impurity atoms interact with a two-dimensional Fermi gas with quadratic band touching the polaron picture may either hold or break down depending on the particle-hole asymmetry of the band structure. If the hole band has a smaller effective mass than the particle band, the quasiparticle is stable and its diffusion coefficient varies with temperature as $D(T) \propto \ln^2 T$. If the hole band has larger mass, the quasiparticle weight vanishes at low energies due to an emergent orthogonality catastrophe. In this case we map the problem onto a set of one-dimensional channels and use conformal field theory techniques to obtain $D(T)\propto T^{\nu}$ with an interaction-dependent exponent $\nu$. The different regimes can be detected in the nonequilibrium expansion dynamics of an initially confined impurity. Comment: 9 pages, 4 figures |
| Databáze: | arXiv |
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