scholarly journals Two-dimensional ground-state mapping of a Mott-Hubbard system in a flexible field-effect device

2019 ◽  
Vol 5 (5) ◽  
pp. eaav7282 ◽  
Author(s):  
Yoshitaka Kawasugi ◽  
Kazuhiro Seki ◽  
Satoshi Tajima ◽  
Jiang Pu ◽  
Taishi Takenobu ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Ground State ◽  
Field Effect ◽  
Mott Insulator ◽  
Two Dimensional ◽  
Superconducting Transition ◽  
Microscopic Mechanism ◽  
One Dimensional ◽  
First Order ◽  
Insulating Phase

A Mott insulator sometimes induces unconventional superconductivity in its neighbors when doped and/or pressurized. Because the phase diagram should be strongly related to the microscopic mechanism of the superconductivity, it is important to obtain the global phase diagram surrounding the Mott insulating state. However, the parameter available for controlling the ground state of most Mott insulating materials is one-dimensional owing to technical limitations. Here, we present a two-dimensional ground-state mapping for a Mott insulator using an organic field-effect device by simultaneously tuning the bandwidth and bandfilling. The observed phase diagram showed many unexpected features such as an abrupt first-order superconducting transition under electron doping, a recurrent insulating phase in the heavily electron-doped region, and a nearly constant superconducting transition temperature in a wide parameter range. These results are expected to contribute toward elucidating one of the standard solutions for the Mott-Hubbard model.

Phase diagram of cuprate high-temperature superconductors based on the optimization Monte Carlo method

2020 ◽  
Vol 34 (19n20) ◽  
pp. 2040046
Author(s):  
T. Yanagisawa ◽  
M. Miyazaki ◽  
K. Yamaji
Keyword(s):  
Phase Diagram ◽  
Monte Carlo ◽  
Wave Function ◽  
High Temperature ◽  
Hubbard Model ◽  
Ground State ◽  
State Energy ◽  
High Temperature Superconductivity ◽  
Two Dimensional ◽  
Text Model

It is important to understand the phase diagram of electronic states in the CuO2 plane to clarify the mechanism of high-temperature superconductivity. We investigate the ground state of electronic models with strong correlation by employing the optimization variational Monte Carlo method. We consider the two-dimensional Hubbard model as well as the three-band [Formula: see text]–[Formula: see text] model. We use the improved wave function that takes account of inter-site electron correlation to go beyond the Gutzwiller wave function. The ground state energy is lowered considerably, which now gives the best estimate of the ground state energy for the two-dimensional Hubbard model. The many-body effect plays an important role as an origin of spin correlation and superconductivity in correlated electron systems. We investigate the competition between the antiferromagnetic state and superconducting state by varying the Coulomb repulsion [Formula: see text], the band parameter [Formula: see text] and the electron density [Formula: see text] for the Hubbard model. We show phase diagrams that include superconducting and antiferromagnetic phases. We expect that high-temperature superconductivity occurs near the boundary between antiferromagnetic phase and superconducting one. Since the three-band [Formula: see text]–[Formula: see text] model contains many-band parameters, high-temperature superconductivity may be more likely to occur in the [Formula: see text]–[Formula: see text] model than in single-band models.

QUANTUM PHASE TRANSITIONS AND ENTANGLEMENT IN J1–J2 MODEL

2004 ◽  
Vol 15 (08) ◽  
pp. 1095-1103 ◽  
Author(s):  
RECEP ERYIĞIT ◽  
RESUL ERYIĞIT ◽  
YIĞIT GÜNDÜÇ
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Phase Transitions ◽  
Ground State ◽  
Abrupt Change ◽  
Quantum Phase Transitions ◽  
Nearest Neighbors ◽  
Competing Interactions ◽  
One Dimensional ◽  
Transition Points

We study ground state pairwise entanglement within one-dimensional spin-1/2 antiferromagnetic J1–J2 model with competing interactions. Contrary to some claims we found that frustration does not increase entanglement. Concurrence of nearest and next nearest neighbors are found to show abrupt change at phase transition points. We also show that the concurrence can be used to classify the phase diagram of the model in anisotropy–frustration plane.

scholarly journals Incommensurate Spin-Density Wave in Two-Dimensional Hubbard Model

2012 ◽  
Vol 190 ◽  
pp. 67-70 ◽  
Author(s):  
M.A. Timirgazin ◽  
Anatoly K. Arzhnikov ◽  
A.V. Vedyayev
Keyword(s):  
Phase Diagram ◽  
Hubbard Model ◽  
Ground State ◽  
Magnetic Phase ◽  
Density Wave ◽  
Spin Density Wave ◽  
Magnetic Phase Diagram ◽  
Two Dimensional ◽  
Magnetic Phases ◽  
Model Relation

We consider the magnetic phase diagram of the two-dimensional Hubbard model ona square lattice.We take into account both spiral and collinear incommensurate magnetic states.The possibility of phase separation of spiral magnetic phases is taken into consideration as well.Our study shows that all the listed phases appear to be the ground state at certain parametersof the model. Relation of the obtained results to real materials, e.g. Cu-based high-temperaturesuperconductors, is discussed.

EFFECTS OF THE NEXT-NEAREST-NEIGHBOR HOPPING IN OPTICAL LATTICES

2008 ◽  
Vol 22 (01) ◽  
pp. 33-44 ◽  
Author(s):  
YUN'E GAO ◽  
FUXIANG HAN
Keyword(s):  
Phase Diagram ◽  
Hubbard Model ◽  
Ground State Energy ◽  
Ground State ◽  
Optical Lattices ◽  
State Energy ◽  
Nearest Neighbor ◽  
Three Dimensional ◽  
Dispersion Relations ◽  
Insulating Phase

Introducing the next-nearest-neighbor hopping t′ into the Bose–Hubbard model, we study its effects on the phase diagram, on the ground-state energy, and on the quasiparticle and quasihole dispersion relations of the Mott insulating phase in optical lattices. We have found that a negative value of t′ enlarges the Mott-insulating region on the phase diagram, while a positive value of t′ acts oppositely. We have also found that the effects of t′ are dependent on the dimensionality of optical lattices with its effects largest in three-dimensional optical lattices.

scholarly journals Emergent BCS regime of the two-dimensional fermionic Hubbard model: Ground-state phase diagram

2015 ◽  
Vol 110 (5) ◽  
pp. 57001 ◽  
Author(s):  
Youjin Deng ◽  
Evgeny Kozik ◽  
Nikolay V. Prokof'ev ◽  
Boris V. Svistunov
Keyword(s):  
Phase Diagram ◽  
Hubbard Model ◽  
Ground State ◽  
Two Dimensional ◽  
Ground State Phase Diagram
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