Half Excitonic Insulator: A Single-Spin Bose-Einstein Condensate

Abstract

First-principles calculations reveal an unusual electronic state (dubbed as half excitonic insulator) in monolayer 1T-MX2 (M = Co, Ni and X = Cl, Br). Its one spin channel has a many-body ground state due to excitonic instability, while the other is characterized by a conventional band insulator gap. This disparity arises from a competition between the band gap and exciton binding energy, which exhibits a spin-dependence due to different orbital occupations. Such a state can be identified by optical absorption measurements and angle-resolved photoemission spectroscopy. Our theory not only provides new insights for the study of exciton condensation in magnetic materials but also suggests that strongly-correlated materials could be fertile candidates for excitonic insulators.

Accepted by PRL

References in corpus (10)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Magic-angle graphene superlattices: a new platform for unconventional superconductivity
• High temperature fractional quantum Hall states
• Ligand-field helical luminescence in a 2D ferromagnetic insulator
• Experimental Signatures of Spin Superfluid Ground State in Canted Antiferromagnet Cr2O3 via Nonlocal Spin Transport
• Optical Selection Rule of Excitons in Gapped Chiral Fermion Systems
• Realizing intrinsic excitonic insulator by decoupling exciton binding energy from the minimum band gap
• Effect of Hartree-Fock Pseudopotential on the First-principles Electronic Structure
• Electric and magnetic multipoles and bond orders in excitonic insulators
• Coherent transport in homojunction between excitonic insulator and semimetal

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