Influence of charge order on the ground states of TMTTF molecular salts

We study a one-dimensional extended Hubbard model with longer-range Coulomb interactions at quarter-filling in the strong coupling limit. We find two different charge-ordered (CO) ground states (Wigner and Peierls) as the strength of the longer range interactions is varied. At lower energies, the two CO states drive different spin-ordered ground states (Heisenberg antiferromagnet and dimerised respectively), reminiscent of the phase diagram of the TMTTF and TMTSF organic charge transfer salts. Several response functions computed in the quantum critical regime bear a remarkable resemblance to recent experimental observations related to CO in the organic TMTTF systems. RPA studies of coupled chains reveal a phase diagram with the ordered phase extended to finite temperatures and a phase boundary ending at a quantum critical point (QCP). Critical quantum fluctuations at the QCP enhance the transverse dispersion, leading to a dimensional crossover and a T = 0 deconfinement transition from insulating chains to anisotropic metallic planar behavior. Numerical estimates for the hierarchy of energy scales associated with charge and spin order and the dimensional crossover compare well with the values obtained experimentally. This leads us to propose that the TMTTF and TMTSF systems are proximate to a QCP associated with T = 0 charge order.

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Charge order and Mott insulating ground states in small-angle twisted bilayer graphene

New Journal of Physics ◽

10.1088/1367-2630/ab950c ◽

2020 ◽

Vol 22 (7) ◽

pp. 073016 ◽

Cited By ~ 1

Author(s):

Markus J Klug

Keyword(s):

Small Angle ◽

Ground States ◽

Charge Order ◽

Bilayer Graphene ◽

Twisted Bilayer Graphene

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Charge order textures induced by non-linear lattice coupling in a half-doped manganite

10.21203/rs.3.rs-103592/v1 ◽

2020 ◽

Author(s):

Ismail El Baggari ◽

David Baek ◽

Michael Zachman ◽

Di Lu ◽

Yasuyuki Hikita ◽

...

Keyword(s):

Ground States ◽

Charge Order ◽

Self Organization ◽

Local Order ◽

Linear Lattice ◽

Transmission Electron ◽

Scanning Transmission ◽

Interacting Electrons ◽

Lattice Coupling ◽

Superlattice Structures

Abstract The self-organization of strongly interacting electrons into superlattice structures underlies the properties of many quantum materials. How these electrons arrange within the superlattice dictates what symmetries are broken and what ground states are stabilized. Here we show that cryogenic scanning transmission electron microscopy enables direct mapping of local symmetries and order at the intra-unit-cell level in the model charge-ordered system Nd1/2Sr1/2MnO3. In addition to imaging the prototypical site-centered charge order, we discover the nanoscale coexistence of an exotic intermediate state which mixes site and bond order and breaks inversion symmetry. We further show that nonlinear coupling of distinct lattice modes controls the selection between competing ground states. The results demonstrate the importance of lattice coupling for understanding and manipulating the character of electronic self-organization and highlight a novel method for probing local order in a broad range of strongly correlated systems.

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Charge order textures induced by non-linear couplings in a half-doped manganite

Nature Communications ◽

10.1038/s41467-021-24026-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Ismail El Baggari ◽

David J. Baek ◽

Michael J. Zachman ◽

Di Lu ◽

Yasuyuki Hikita ◽

...

Keyword(s):

Ground States ◽

Charge Order ◽

Atomic Scale ◽

Self Organization ◽

Local Order ◽

Strongly Correlated ◽

Transmission Electron ◽

Scanning Transmission ◽

Interacting Electrons ◽

Superlattice Structures

AbstractThe self-organization of strongly interacting electrons into superlattice structures underlies the properties of many quantum materials. How these electrons arrange within the superlattice dictates what symmetries are broken and what ground states are stabilized. Here we show that cryogenic scanning transmission electron microscopy (cryo-STEM) enables direct mapping of local symmetries and order at the intra-unit-cell level in the model charge-ordered system Nd1/2Sr1/2MnO3. In addition to imaging the prototypical site-centered charge order, we discover the nanoscale coexistence of an exotic intermediate state which mixes site and bond order and breaks inversion symmetry. We further show that nonlinear coupling of distinct lattice modes controls the selection between competing ground states. The results demonstrate the importance of lattice coupling for understanding and manipulating the character of electronic self-organization and that cryo-STEM can reveal local order in strongly correlated systems at the atomic scale.

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