All Questions
Tagged with spin-models quantum-spin
86
questions
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Magnetization derivation for non-Ising systems
Can anyone help get me started on deriving a more general magnetization for non-Ising systems? I cannot find any information on a general derivation of the magnetization of 1D, 2D, or 3D systems of ...
0
votes
1
answer
102
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Integrability of spin central model
I have a central model of this form $$H = \sum_{i=1}^{N} S^z_0\otimes S^z_i$$ where the $S^z_i$ acts on the $i$th element of the environment, i.e. the Hilbert space is of the following form $\mathcal{...
- 565
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53
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Ising configuration after rotation in one sub-lattice
I do not understand Eq. (5.9) in Auerbach's book Interacting electrons an quantum magnetism. Consider the general spin-$S$ Heisenberg model on a bipartite lattice with $N$ sites:
$$
H = \frac{1}{2} \...
- 660
3
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237
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Neel ordering on the square lattice vs mean-field AFM Heisenberg model
Question:
It seems like the Neel order of the AFM Heisenberg model on the square lattice is actually stronger than the (bipartite) fully-connected case. This seems counterintuitive. Am I simply wrong ...
- 321
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Must spin glasses really have an exponential density of states close to the ground state?
I'm a complete beginner to spin glasses. I'm not even sure of the definition; I've mostly seen examples, like Sherrington-Kirkpatric with all-all pairwise normally distributed Ising interactions. ...
- 2,292
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1
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676
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Transverse-field Ising model in the presence of a longitudinal field - ferromagnetic phase diagram
I am wondering what is the phase diagram of the transverse-field Ising model in the presence of a longitudinal field, in particular, a one-dimensional spin-1/2 chain with ferromagnetic interactions. ...
- 21
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53
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How to handle Dzyaloshinkii-Moriya imaginary terms in Heisenberg chain?
The DM interaction has three coordinate-specific terms when splitting it up. Two of these, the DM-x and DM-z terms, are imaginary when we transform them into series of raising and lowering operators. ...
- 11
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Correlation functions of XY quantum chain
I'm trying to understand the calculation of the correlation functions in the XY quantum chain performed by Lieb, Mattis and Schultz in the paper "Two Solvable Models of an antiferromagnetic chain&...
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61
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Orientation of spin operators in Heisenberg model
What is meant by orientation of a spin operator (in, for example, Heisenberg model in condensed matter physics)?
For example, in Ising model we have Hamiltonian $H=\displaystyle\sum_{i,j}J_{ij}S_{i}S_{...
- 115
4
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141
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Energy gap of a Heisenberg model on bipartite lattices
Consider the antiferromagnetic Heisenberg model on some "graph" where each vertex corresponds to a spin-1/2 and the edges represent interaction between the vertices, i.e.,
\begin{equation}
\...
- 321
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52
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Possible (Minor) Error in Original Lieb-Robinson Bound Paper
Introduction
I was reading through Lieb and Robinson's original paper introducing their eponymous bounds, and I came upon the following statement:
The task remains of corroborating our assertions ...
3
votes
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559
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Static spin structure factor VS equal-time spin structure factor
It looks like many papers (maybe all papers containing "static spin structure factor") use the terminology, static spin structure factor, to refer to the equal-time spin structure factor ...
- 123
4
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89
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Operator inequality between the Heisenberg Hamiltonian and the total spin
Consider a collection of $N$ spin-1/2 particles (qubits) with total spin
$$\vec{S} = \frac{1}{2}\sum_{n=1}^N \vec{\sigma}_n$$
and a Heisenberg Hamiltonian
$$H = -J \sum_{\langle n,m\rangle} \vec{\...
- 3,684
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What is meant by spin temperature in the context of ultrafast demagnetization's three-temperature model?
Ultrafast demagnetization and associated fields often refer to the three-temperature model introduced by Beaurepaire. As the abstract says:
The relaxation processes of electrons and spins systems ...
- 46
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Bogoliubov-Valatin transformation generalisation
Considering the following Heisenberg Hamiltonian (with spin $S$ , and $J<0$ for the case of an antiferromagnet) when we only consider interactions between first neighbors in a square lattice in the ...
- 1,124