Exact diagonalization of the full propagator in IQHE and FQHE configurations

1991 ◽  
Vol 157 (8-9) ◽  
pp. 527-531 ◽  
Author(s):  
A. Cabo ◽  
M. Chaichian
Keyword(s):  
Exact Diagonalization ◽  
Full Propagator

scholarly journals Anomalous and anisotropic nonlinear susceptibility in the proximate Kitaev magnet α-RuCl3

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Ludwig Holleis ◽  
Joseph C. Prestigiacomo ◽  
Zhijie Fan ◽  
Satoshi Nishimoto ◽  
Michael Osofsky ◽  
...  
Keyword(s):  
Low Temperatures ◽  
High Field ◽  
Magnetic Order ◽  
Exact Diagonalization ◽  
Nonlinear Susceptibility ◽  
Magnetic Response ◽  
Leading Order ◽  
Rapid Rise ◽  
Quadratic Response ◽  
Antiferromagnetic Behavior

AbstractThe leading order nonlinear (NL) susceptibility, χ3, in a paramagnet is negative and diverges as T → 0. This divergence is destroyed when spins correlate and the NL response provides unique insights into magnetic order. Dimensionality, exchange interaction, and preponderance of quantum effects all imprint their signatures in the NL magnetic response. Here, we study the NL susceptibilities in the proximate Kitaev magnet α-RuCl3, which differs from the expected antiferromagnetic behavior. For T < Tc = 7.5 K and field B in the ab-plane, we obtain contrasting NL responses in low (<2 T) and high field regions. For low fields, the NL behavior is dominated by a quadratic response (positive χ2), which shows a rapid rise below Tc. This large χ2 > 0 implies a broken sublattice symmetry of magnetic order at low temperatures. Classical Monte Carlo (CMC) simulations in the standard K − H − Γ model secure such a quadratic B dependence of M, only for T ≈ Tc with χ2 being zero as T → 0. It is also zero for all temperatures in exact diagonalization calculations. On the other hand, we find an exclusive cubic term (χ3) that describes the high field NL behavior well. χ3 is large and positive both below and above Tc crossing zero only for T > 50 K. In contrast, for B ∥ c-axis, no separate low/high field behaviors are measured and only a much smaller χ3 is apparent.

SPIN STRUCTURES IN INHOMOGENEOUS FRACTIONAL QUANTUM HALL SYSTEMS

2004 ◽  
Vol 18 (27n29) ◽  
pp. 3871-3874 ◽  
Author(s):  
KAREL VÝBORNÝ ◽  
DANIELA PFANNKUCHE
Keyword(s):  
Ground State ◽  
Quantum Hall ◽  
Exact Diagonalization ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Spin Structures ◽  
Quantum Hall Systems ◽  
Magnetic Inhomogeneities ◽  
Spin Singlet ◽  
Spin Polarized

Transitions between spin polarized and spin singlet incompressible ground state of quantum Hall systems at filling factor 2/3 are studied by means of exact diagonalization with eight electrons. We observe a stable exactly half–polarized state becoming the absolute ground state around the transition point. This might be a candidate for the anomaly observed during the transition in optical experiments. The state reacts strongly to magnetic inhomogeneities but it prefers stripe–like spin structures to formation of domains.

Effects of a magnetic field in Kondo insulators: An exact diagonalization study of the Anderson lattice model

1997 ◽  
Vol 230-232 ◽  
pp. 421-424 ◽  
Author(s):  
K. Tsutsui ◽  
Y. Ohta ◽  
R. Eder ◽  
S. Maekawa ◽  
E. Dagotto ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Lattice Model ◽  
Exact Diagonalization ◽  
Kondo Insulators

Two-Step Evolution of the Quasiparticle Band with Doping in the Two-Dimensional t-t′-t″-J Model

1998 ◽  
Vol 12 (29n31) ◽  
pp. 2914-2919
Author(s):  
Chang-De Gong ◽  
Wei-Guo Yin ◽  
P. W. Leung
Keyword(s):  
Theoretical Analysis ◽  
Excellent Agreement ◽  
Exact Diagonalization ◽  
Flat Band ◽  
Two Dimensional ◽  
Doping Dependence ◽  
Flat Region ◽  
Half Filling ◽  
Quasiparticle Band

We study the doping dependence of photoemission spectra for the t-t′-t″-J model by using the exact diagonalization technique and present a consistent theoretical analysis. Both calculations show that upon doping the enhancement of incoherent motion of holes due to the t′ and t″ terms accounts for the formation of the flat region around (π,0) in the quasiparticle dispersion at underdoped and optimally doped region, despite the absence of the flat band at half filling. Our results are in excellent agreement with resent photoemission experiments on Bi 2 Sr 2 Ca 1 Cu 2 O 8+δ [Marshall et al., Phys. Rev. Lett.76, 4841 (1996)] and Sr 2 CuO 2 Cl 2 [Wells et al., Phys. Rev. Lett.74, 964 (1995)].

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