scholarly journals Topological excitations in a two-dimensional spin system with high spin s ≥1

2009 ◽  
Vol 160 (1) ◽  
pp. 878-886 ◽  
Author(s):  
J. N. Bernatska ◽  
P. I. Holod
Keyword(s):  
High Spin ◽  
Spin System ◽  
Two Dimensional ◽  
Topological Excitations

scholarly journals EFFECTIVE THEORY FOR A QUANTUM SPIN SYSTEM IN LOW DIMENSIONS – BEYOND THE LONG WAVELENGTH LIMIT

2002 ◽  
Vol 16 (08) ◽  
pp. 251-259 ◽  
Author(s):  
RANJAN CHAUDHURY ◽  
SAMIR K. PAUL
Keyword(s):  
Spin System ◽  
Quantum Spin ◽  
Effective Theory ◽  
Quantum Spin System ◽  
Partition Functions ◽  
Two Dimensional ◽  
Low Dimensions ◽  
Topological Excitations ◽  
Long Wavelength ◽  
Wavelength Limit

An effective theory for a quantum spin system in low dimensions is constructed in the finite-q regime. It is shown that there are field configurations for which Wess–Zumino terms contribute to the partition functions as topological terms for ferromagnets as well as antiferromagnets in both one- and two-dimensional lattices. This is in sharp contrast to the absence of topological excitations in two-dimensional quantum antiferromagnets in the long wavelength limit.

scholarly journals The connection between vortex-like topological excitations and conventional excitations in quantum ferromagnetic spin systems on two-dimensional lattice and their stability

2015 ◽  
Vol 29 (29) ◽  
pp. 1550209
Author(s):  
Subhajit Sarkar ◽  
Ranjan Chaudhury ◽  
Samir K. Paul
Keyword(s):  
Nearest Neighbor ◽  
Magnetic Measurements ◽  
Spin Dynamics ◽  
Threshold Value ◽  
System Size ◽  
Heisenberg Ferromagnet ◽  
Two Dimensional ◽  
Stable States ◽  
Dimensional Lattice ◽  
Topological Excitations

In this paper, we present a scheme for the construction of quantum states of vortex-like topological excitations corresponding to spin-1/2 strongly XY-anisotropic nearest neighbor Heisenberg ferromagnet on two-dimensional lattice. The procedure involving Pauli spin basis states is carried out corresponding to both infinite dilute limit and finite density limit of vortex/anti-vortex. It is found that the corresponding quantum mechanical states representing charge 1 quantum vortices/anti-vortices can be expressed as linear combinations of single magnon states, composite multi-magnon states and the ground state. Detailed calculations show that these states are quantum mechanically stable states of the Hamiltonian only when the system size exceeds certain threshold value. Our analysis indicates that the interactions between different magnon modes can very well generate these topological excitations. Possible applications of our calculations to real magnetic systems are also discussed. Magnetic measurements probing spin dynamics may be undertaken to verify the existence of the threshold size for the stability of vortices.

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