2016/07/08 by Abhisek Samanta, Rajdeep Sensarma
Physics and Astronomy · #Advanced Condensed Matter Physics #Antiferromagnetism #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Hubbard model #Ion #Ionic bonding #Mott insulator #Paramagnetism #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Quasiparticle #Superconductivity #Superfluidity #cond-mat.quant-gas #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.94.224517
published as Phys. Rev. B 94, 224517 (2016)
arxiv created 2016/07/08 · openalex publication_date 2016/12/27 · arxiv updated 2017/01/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In the ionic Hubbard model, the on-site repulsion U, which drives a Mott insulator, and the ionic potential V, which drives a band insulator, compete with each other to open up a window of charge fluctuations when U\ensuremath∼V. We study this model on square and cubic lattices in the limit of large U and V, with V\ensuremath∼U. Using an effective Hamiltonian and a slave-boson approach with both doublons and holons, we find that the system undergoes a phase transition as a function of V from an antiferromagnetic Mott insulator to a paramagnetic insulator with strong singlet correlations, which is driven by a condensate of ``neutral'' doublon-holon pairs. On further increasing V, the system undergoes another phase transition to a superconducting phase driven by condensate of ``charged'' doublons and holons. The superfluid phase, characterized by the presence of a coherent (but gapped) fermionic quasiparticle and hc/e flux quantization, has a high Tc\ensuremath∼t, which shows a dome-shaped behavior as a function of V. The paramagnetic insulator phase has a deconfined U(1) gauge field and associated gapless photon excitations. We also discuss how these phases can be detected in the ultracold-atom context.