scholarly journals Exciton formation in strongly correlated electron-hole systems near the semimetal-semiconductor transition

2014 ◽  
Vol 529 ◽  
pp. 012030 ◽  
Author(s):  
B Zenker ◽  
D Ihle ◽  
F X Bronold ◽  
H Fehske
Keyword(s):  
Strongly Correlated ◽  
Electron Hole ◽  
Strongly Correlated Electron ◽  
Correlated Electron

scholarly journals Exciton-driven antiferromagnetic metal in a correlated van der Waals insulator

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Carina A. Belvin ◽  
Edoardo Baldini ◽  
Ilkem Ozge Ozel ◽  
Dan Mao ◽  
Hoi Chun Po ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Van Der Waals ◽  
Metallic State ◽  
Strongly Correlated ◽  
Many Body ◽  
Electron Hole ◽  
Strongly Correlated Electron ◽  
Long Wavelength ◽  
Correlated Electron ◽  
Strongly Correlated Electron Materials

AbstractCollective excitations of bound electron-hole pairs—known as excitons—are ubiquitous in condensed matter, emerging in systems as diverse as band semiconductors, molecular crystals, and proteins. Recently, their existence in strongly correlated electron materials has attracted increasing interest due to the excitons’ unique coupling to spin and orbital degrees of freedom. The non-equilibrium driving of such dressed quasiparticles offers a promising platform for realizing unconventional many-body phenomena and phases beyond thermodynamic equilibrium. Here, we achieve this in the van der Waals correlated insulator NiPS3 by photoexciting its newly discovered spin–orbit-entangled excitons that arise from Zhang-Rice states. By monitoring the time evolution of the terahertz conductivity, we observe the coexistence of itinerant carriers produced by exciton dissociation and a long-wavelength antiferromagnetic magnon that coherently precesses in time. These results demonstrate the emergence of a transient metallic state that preserves long-range antiferromagnetism, a phase that cannot be reached by simply tuning the temperature. More broadly, our findings open an avenue toward the exciton-mediated optical manipulation of magnetism.

GROUND STATE INSTABILITY OF STRONGLY CORRELATED ELECTRONS

1992 ◽  
Vol 06 (16n17) ◽  
pp. 1063-1068
Author(s):  
A. FERRAZ ◽  
Y. OHMURA
Keyword(s):  
Ground State ◽  
Strongly Correlated Electrons ◽  
Electron System ◽  
Strongly Correlated ◽  
Coulomb Interactions ◽  
Electron Hole ◽  
Strongly Correlated Electron ◽  
Correlated Electron ◽  
Scattering Kernel ◽  
Electronic Ground

Summing up a special series of skeleton diagrams we show that in a strongly correlated electron fluid the proper irreducible electron-hole scattering kernel K is singular for sufficiently large Coulomb interactions. The instability of the electronic ground state is exhibited in the purely imaginary pole of K. This pole determines the decay rate of the unstable ground state and signals a phase transition of the whole electron system.

scholarly journals Electrical transport properties and Kondo effect in La1−xPrxNiO3−δ thin films

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Van Hien-Hoang ◽  
Nak-Kwan Chung ◽  
Heon-Jung Kim
Keyword(s):  
Thin Films ◽  
Electrical Transport ◽  
Kondo Effect ◽  
Magnetic Moments ◽  
Structural Disorder ◽  
Strongly Correlated ◽  
Electrical Transport Properties ◽  
Strongly Correlated Electron ◽  
Correlated Electron Systems ◽  
Correlated Electron

AbstractThe Kondo effect has been a topic of intense study because of its significant contribution to the development of theories and understanding of strongly correlated electron systems. In this work, we show that the Kondo effect is at work in La1−xPrxNiO3−δ (0 ≤ x ≤ 0.6) thin films. At low temperatures, the local magnetic moments of the 3d eg electrons in Ni2+, which form because of oxygen vacancies, interact strongly with itinerant electrons, giving rise to an upturn in resistivity with x ≥ 0.2. Observation of negative magnetoresistance, described by the Khosla and Fisher model, further supports the Kondo picture. This case represents a rare example of the Kondo effect, where Ni2+ acts as an impurity in the background of Ni3+. We suggest that when Ni2+ does not participate in the regular lattice, it provides the local magnetic moments needed to scatter the conduction electrons in the Kondo effect. These results offer insights into emergent transport behaviors in metallic nickelates with mixed Ni3+ and Ni2+ ions, as well as structural disorder.

EXACTNESS OF FERMIONIC LINEARIZATION SCHEME WITH CLIFFORD VARIABLES IN d=∞

1995 ◽  
Vol 09 (16) ◽  
pp. 971-975 ◽  
Author(s):  
ARIANNA MONTORSI
Keyword(s):  
Exact Solution ◽  
Single Site ◽  
Strongly Correlated Electron Systems ◽  
Strongly Correlated ◽  
Electron Systems ◽  
Strongly Correlated Electron ◽  
Correlated Electron Systems ◽  
Correlated Electron

We show that the fermionic linearization scheme for dealing with strongly correlated electron systems — when implemented with Clifford variables — becomes exact in the d=∞ limit, at least for Hubbard-like models. In this case, the model is mapped exactly into a single-site problem. The conditions under which such a feature allows to obtain an exact solution are also discussed.

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