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Lithium Intercalation into the Excitonic Insulator Candidate Ta2NiSe5
P A Hyde1, J Cen2,3, S J Cassidy1
1Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
Inorganic Chemistry
|July 19, 2023
Summary
Lithium intercalation in Ta2NiSe5 creates a new metallic phase, LiTa2NiSe5. This new phase suppresses the excitonic insulating state and distortion observed in the parent compound.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid-State Chemistry
Background:
- Ta2NiSe5 is an excitonic insulator candidate exhibiting a structural distortion at 328 K.
- Understanding phase transitions and electronic properties of layered materials is crucial.
Purpose of the Study:
- To synthesize and characterize a new reduced phase of Ta2NiSe5 via lithium intercalation.
- To investigate the structural, electronic, and magnetic properties of the intercalated compound LiTa2NiSe5.
Main Methods:
- Synthesis of LiTa2NiSe5 through lithium intercalation.
- Neutron powder diffraction for structural analysis.
- Li-NMR spectroscopy for local Li environment.
- Magnetometry for magnetic susceptibility measurements.
- Computational analysis (DFT) for electronic structure.
Main Results:
- LiTa2NiSe5 crystallizes in an orthorhombic structure (Pmnb), with increased unit cell volume.
- Lithium atoms occupy distorted triangular prismatic sites between Ta2NiSe5 layers.
- Intercalation suppresses the monoclinic distortion and excitonic insulating state of the parent material.
- LiTa2NiSe5 exhibits enhanced Pauli paramagnetism, indicating a metallic phase.
Conclusions:
- Lithium intercalation transforms the excitonic insulator candidate Ta2NiSe5 into a metallic phase.
- The structural and electronic changes are attributed to electron injection and suppression of the excitonic insulating state.
- LiTa2NiSe5 presents a new platform for studying electron-correlated phenomena in layered materials.
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