Low-lying spin-wave spectrum of the triangular anti-ferromagnet: A finite-size study

2001 ◽  
Vol 79 (11-12) ◽  
pp. 1537-1542
Author(s):  
A E Trumper ◽  
L Capriotti ◽  
S Sorella
Keyword(s):  
Spin Wave ◽  
Quantum Monte Carlo ◽  
Wave Spectrum ◽  
Finite Size ◽  
Low Energy ◽  
Energy Excitation ◽  
Spin Excitations ◽  
Spin Wave Spectrum ◽  
Wave Calculation ◽  
Good Agreement

We developed a finite-size spin-wave calculation on the Heisenberg anti-ferromagnet on the triangular lattice, which, to order 1/s, favors a singlet (for an even number of sites) ground state. Furthermore, we implement the computation of the low-energy excitation spectrum E (S) where S is the total spin. For s=1/2, the good agreement with the exact diagonalization and quantum Monte Carlo results strengthens the validity of the spin-wave expansion to describe the low-energy spin excitations of the Heisenberg model even in the presence of frustration. PACS No.: 75.10-b

scholarly journals QUANTUM EFFECTS AND BROKEN SYMMETRIES IN FRUSTRATED ANTIFERROMAGNETS

2001 ◽  
Vol 15 (12) ◽  
pp. 1799-1842 ◽  
Author(s):  
LUCA CAPRIOTTI
Keyword(s):  
Monte Carlo ◽  
Excitation Spectrum ◽  
Spin Wave ◽  
Ground State ◽  
Quantum Monte Carlo ◽  
Finite Size ◽  
Wave Theory ◽  
Low Energy ◽  
Heisenberg Antiferromagnet ◽  
Néel Order

We investigate the interplay between frustration and zero-point quantum fluctuations in the ground state of the triangular and J1–J2 Heisenberg antiferromagnets, using finite-size spin-wave theory, exact diagonalization, and quantum Monte Carlo methods. In the triangular Heisenberg antiferromagnet, by performing a systematic size-scaling analysis, we have obtained strong evidences for a gapless spectrum and a finite value of the thermodynamic order parameter, thus confirming the existence of long-range Néel order. The good agreement between the finite-size spin-wave results and the exact and quantum Monte Carlo data also supports the reliability of the spin-wave expansion to describe both the ground state and the low-energy spin excitations of the triangular Heisenberg antiferromagnet. In the J1–J2 Heisenberg model, our results indicate the opening of a finite gap in the thermodynamic excitation spectrum at J2/J1≃0.4, marking the melting of the antiferromagnetic Néel order and the onset of a non-magnetic ground state. In order to characterize the nature of the latter quantum-disordered phase we have computed the susceptibilities for the most important crystal symmetry breaking operators. In the ordered phase the effectiveness of the spin-wave theory in reproducing the low-energy excitation spectrum suggests that the uniform spin susceptibility of the model is very close to the linear spin-wave prediction.

Spin-Wave Spectrum in the Sinusoidal Superlattice with Amplitude and Phase Inhomogeneities

2014 ◽  
Vol 215 ◽  
pp. 385-388
Author(s):  
Valter A. Ignatchenko ◽  
Denis S. Tsikalov
Keyword(s):  
Spin Wave ◽  
Density Of States ◽  
Wave Spectrum ◽  
The Self ◽  
One Dimensional ◽  
Consistent Approximation ◽  
Self Consistent ◽  
Greens Function ◽  
The One ◽  
Spin Wave Spectrum

Effects of both the phase and the amplitude inhomogeneities of different dimensionalities on the Greens function and on the one-dimensional density of states of spin waves in the sinusoidal superlattice have been studied. Processes of multiple scattering of waves from inhomogeneities have been taken into account in the self-consistent approximation.

Spin wave spectrum of quasi-two-dimensional antiferromagnet NH3(CH2)2NH3MnCl4

1994 ◽  
Vol 194-196 ◽  
pp. 187-188 ◽  
Author(s):  
V.V. Eremenko ◽  
V.I. Fomin ◽  
V.S. Kurnosov
Keyword(s):  
Spin Wave ◽  
Wave Spectrum ◽  
Two Dimensional ◽  
Spin Wave Spectrum

scholarly journals Конденсация (псевдо)магнонов в двумерной анизотропной S=1 (псевдо)спиновой системе

2018 ◽  
Vol 60 (11) ◽  
pp. 2105
Author(s):  
Е.В. Васинович ◽  
А.С. Москвин ◽  
Ю.Д. Панов
Keyword(s):  
Phase Transition ◽  
Spin Wave ◽  
Superconducting State ◽  
Ground State ◽  
Wave Spectrum ◽  
Hard Core ◽  
Boson Systems ◽  
Variable Valence ◽  
Anisotropic System ◽  
Spin Wave Spectrum

Abstract —A 2D anisotropic system of S = 1 centers of the charge triplet type in systems with variable valence or “semi-hard-core” boson systems with a limitation for the occupation of lattice sites n = 0, 1, 2 is studied in the framework of the pseudospin formalism. Assuming that the ground state is a quantum paramagnet, the pseudo-spin wave spectrum and also the conditions of the condensation of pseudomagnons with a phase transition to a superconducting state have been found using the Schwinger boson method.

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