Nature of Symmetry Breaking at the Excitonic Insulator Transition: Ta_{2}NiSe_{5}.

Autor:	Mazza G; Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211 Geneva, Switzerland.; CPHT, CNRS, Ecole Polytechnique, IP Paris, F-91128 Palaiseau, France.; Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France., Rösner M; Radboud University, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ Nijmegen, Netherlands., Windgätter L; Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany., Latini S; Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany., Hübener H; Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany., Millis AJ; Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA.; Department of Physics, Columbia University, New York, New York 10027, USA., Rubio A; Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany.; Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA.; Nano-Bio Spectroscopy Group, Departamento de Física de Materiales, Universidad del País Vasco, 20018 San Sebastian, Spain., Georges A; Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211 Geneva, Switzerland.; CPHT, CNRS, Ecole Polytechnique, IP Paris, F-91128 Palaiseau, France.; Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France.; Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA.
Jazyk:	angličtina
Zdroj:	Physical review letters [Phys Rev Lett] 2020 May 15; Vol. 124 (19), pp. 197601.
DOI:	10.1103/PhysRevLett.124.197601
Abstrakt:	Ta_{2}NiSe_{5} is one of the most promising materials for hosting an excitonic insulator ground state. While a number of experimental observations have been interpreted in this way, the precise nature of the symmetry breaking occurring in Ta_{2}NiSe_{5}, the electronic order parameter, and a realistic microscopic description of the transition mechanism are, however, missing. By a symmetry analysis based on first-principles calculations, we uncover the discrete lattice symmetries which are broken at the transition. We identify a purely electronic order parameter of excitonic nature that breaks these discrete crystal symmetries and contributes to the experimentally observed lattice distortion from an orthorombic to a monoclinic phase. Our results provide a theoretical framework to understand and analyze the excitonic transition in Ta_{2}NiSe_{5} and settle the fundamental questions about symmetry breaking governing the spontaneous formation of excitonic insulating phases in solid-state materials.
Databáze:	MEDLINE
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