- Linear spin wave theory for the frustrated ferromagnetic spin.
- Spin-Wave Wave Function for Quantum Spin Models.
- (PDF) A step-by-step Bogoliubov transformation method for.
- Microscopic theory of dipole-exchange spin-wave excitations in.
- Bogoliubov transformation - Detailed Pedia.
- Journal of Physics B: Atomic, Molecular and... - IOPscience.
- Mathematics authors/titles "new" - arXiv.
- On Spin-Statistics and Bogoliubov Transformations in Flat.
- Flow equations and extended Bogoliubov transformation for the.
- Stark effects in rutile antiferromagnets — Experts@Minnesota.
- PDF Mathematical Analysis of the BCS-Bogoliubov Theory 1 Introduction.
- Linear spin wave theory for the frustrated... - ScienceDirect.
- Holstein-Primakoff and Bogoliubov transformation - 知乎.
- PDF Spin Nernst Effect of Magnons in Collinear Antiferromagnets.
Linear spin wave theory for the frustrated ferromagnetic spin.
In this paper we present a generalization of the SWT that allows for describing the low-energy modes of spin systems with arbitrary orderings (spontaneous or induced by external fields). The resulting method has been applied to several models (e.g., Refs. [ 1-7 ]). Conventional spin wave expansion transformations -Holstein-Primakoff -Fourier transformation using reduced BZ -diagonalization: Bogoliubov transformation H^ = 1 2 X ij JijSi¢SjJij=J>0 H = Ecl+H2+H4+O(b6) Ecl= ¡DNJS2 H2= S X ij Jij ³ by ibi+b y jbj+bibj+b y ib y j ´ bi= r 2 N X k eik¢riA kbi= r 2 N X k eik¢riB k µ Ak By ¡k ¶ = µ ukvk ¡vkuk ¶µ ®k.
Spin-Wave Wave Function for Quantum Spin Models.
For generick,l,m,nthe product of wave functions is rapidly oscillating as a function orrthus suppressing the value of the integral (the charac- teristic length scale for the oscillations is set by the Fermi wavelength) and making it zero on average. Havingk=n,l=mork=m,l=nreduces the product of wavefunctions to. Made available by U.S. Department of Energy Office of Scientific and Technical Information. Spin-wave theory ~SWT! and the quantum Monte Carlo method ~QMC!, which is confirmed by Kolezhuket al.3 with the matrix product approach. It is also consistent with... Then the angle of the Bogoliubov transformation is ex-pressed in a compact form cosh2uk5 1 A12h2g k 2, sinh2uk5 uhgku 12h2g k 2, ~10! and the self-consistent equations read.
(PDF) A step-by-step Bogoliubov transformation method for.
Linear spin wave theory provides the leading term in the calculation of the excitation spectra of long-range ordered magnetic systems as a function of $1/\\sqrt{S}$. This term is acquired using the Holstein-Primakoff approximation of the spin operator and valid for small $δS$ fluctuations of the ordered moment. We propose an algorithm that allows magnetic ground states with general moment. The book is dedicated to the study of theoretical tools in spin models in magnetism. The book presents the basic tools to treat spin models in magnetic systems such as: spin waves, Schwinger bosons formalism, Self-consistent harmonic approximation, Kubo theory, Perturbation theory using Green's function.
Microscopic theory of dipole-exchange spin-wave excitations in.
The systems involving non-trivial Bogoliubov transformations contain dynamics which point to commutation relations. Particles described by in-modes obey the same statistics as particles described. In this chapter, the spin-wave formalism is presented for the ferromagnet and the antiferromagnet. The XY model is studied using a self-consistent harmonic approximation. The chapter is finished with a brief introduction to the Jordan-Wigner transformation and Majorana fermions. After a transformation of the diffusion problem onto the fixed domain, we use the formal method of two-scale asymptotic expansion to derive the upscaled model, which is nonlinearly coupled through effective coefficients. The effective model is implemented and validated using an application-inspired model problem.
Bogoliubov transformation - Detailed Pedia.
Can be diagonalized via a bosonic Bogoliubov transformation T(q). The spin-wave dispersions of other magnetic orderings (including the mixed phase and the noncollinear phase) are shown in.
Journal of Physics B: Atomic, Molecular and... - IOPscience.
Using the variational approach for a trial wave function of a predetermined form and... (Bogoliubov-De Jennes transformation [9]) and in calculation of spin-wave excitation spectrum in antiferromagnets where also "dangerous" diagrams appear. [1] J. Bardeen, L. Cooper, and J. Schrieffer, Phys. Rev. 106, 162 (1957).. Introduction The Bogoliubov transformation Quasiparticle representation The HFB equation The HFB in canonical basis The constraint HFB calculation The multi-quasiparticle states The temperature-dependent HFB in rotating frame Introduction In the Hartree-Fock-Bogoliubov (HFB) method, the ground-state wave function is de. Motivated by recent experiments on thin films of the ferromagnetic insulator yttrium-iron garnet (YIG), we have developed an efficient microscopic approach to calculate the spin-wave spectra of these systems. We model the experimentally relevant magnon band of YIG using an effective quantum Heisenberg model on a cubic lattice with ferromagnetic nearest neighbour exchange and long-range dipole.
Mathematics authors/titles "new" - arXiv.
Dec 01, 2021 · The Bogoliubov transformation is used to diagonalize the Hamiltonian analytically, that gives an expression of the spin wave spectrum ω k. From analyzing the behavior of the spectrum curve, we have found that relation between the pitch angle and the frustration parameter, i.e. φ = arccos ( 1 4 α ) can be derived as a result of our analyses. Here by studying the Hamiltonian , rather than constructing a Bogoliubov transformation as conventionally, we are going to illustrate an alternative method which is able to analytically solve spin wave excitations for the cases of multi-spin unit cells. This method employs the equation of motion to construct a secular equation, i.e. an.
On Spin-Statistics and Bogoliubov Transformations in Flat.
Goldstone modes, and spin-wave theory. Using the Neel state as the broken symmetry state one might think we should be able to find spin-wave excitations which we know are gapless, and lead to power law correlations.... Bogoliubov transformation The Bogoliubov transformation, ck = ukak −vkb. Look at conventional spinwave expansion for QAF: (Anderson 1952, Kubo 1952, Oguchi 1960) 3 Transformations: 1.) HolsteinPrimakoff: mapping onto bosonproblem 2.) Fourier transformation in sublattice basis: on sublattice A: on sublattice B: 3.)Bogoliubov transformation. Two Sublattices HP Transformation A B A sublattice B sublattice. Antiferromagnetic Spin Wave Bogoliubov transformation. Spin Wave in La2CuO4. S=1/2 Heisenberg antiferromagnet on square lattice Magnon excitations spin-wave theory Linear Data points for Cu(DCOO)2 4D20.
Flow equations and extended Bogoliubov transformation for the.
In the zero external field limit and for a spin 1/2 lattice the bound M(β) is implicitly given by the equation 1 - M = 2M(2π)"M j dnp(eβE^IM-ί)'1, (1) where β is the inverse temperature and E p stands for the energy of a spin wave with momentum p. The integration is carried over the first Brillouin zone. By inspection,.
Stark effects in rutile antiferromagnets — Experts@Minnesota.
Method to wave functions with odd particle numbers. We defer details of our new code to later publication [22]. For the present purposes, the main points on the computational side are the definition of the basis states and the assumed block structure of the Bogoliubov transformation matrices UV.We. Apr 12, 2020 · where γ k = 1 / z ∑ δ e i k ⋅ δ. And z is number of NN and δ is location of NN. to diagonalize apply Bogoliubov transformation α k = u k a k − v k b − k +; β k + = − v k a k + u k b − k + this gives us the following results H 1 = ∑ k ϵ k ( α k + α k + β k + β k) where ϵ k = z J S ∑ k 1 − γ k 2 My question: Till 2nd step, I know what's going on. We show that, as a consequence of the fact that the Bogoliubov transformation mixes spin waves on different sublattices, the phenomenological Loudon Hamiltonian describing the two spin-wave absorption in rutile antiferromagnets also predicts a linear Stark effect on the two spin-wave line in these materials in the presence of dc electric fields.
PDF Mathematical Analysis of the BCS-Bogoliubov Theory 1 Introduction.
2.3 Model system 1: Linear spin-wave theory Geometry (thin film) Numerical approach Ewald summation technique Diagonalization of 2N x 2N matrix Analytic approaches Approximation for lowest mode Bogoliubov transformation No dipolar interaction: known result H 2 = Ã A ~ k B ~ k B ¤ ¡ ~ k ¡ A T ¡ ~ k! E ~ k = q [h + ½ ex ~ k 2 + ¢(1 ¡ f.
Linear spin wave theory for the frustrated... - ScienceDirect.
We complete the antiferromagnetic case from last time, where the ground state of the original HP bosons is not the ground state of the new operators created by a bosonic Bogoliubov transformation. Our result for the spin-wave spectrum of the antiferromagnet was. Magnetic order exists as a ground state property only, below some critical temperature at which a phase transition takes place. It can be described using the molecular or mean field approximation. For spin excitations at the surface of magnetic solids ( surface magnons) we refer to [179, 180]. Keywords Spin Wave Elementary Excitation. We theoretically investigate one-dimensional three-component spin-orbit-coupled Fermi gases in the presence of the Zeeman field. By solving the Bogoliubov-de Gennes equations, we obtain the phase diagram at a given chemical potential and order parameter. We show that, with increasing the intensity of the Zeeman field, in addition to undergoing a phase transition from Bardeen-Cooper-Schrieffer.
Holstein-Primakoff and Bogoliubov transformation - 知乎.
If such quantum melting takes place our linear spin wave approxima-tion is not valid anymore. The number of bosons in the groundstate will become large and the linearized form of the spinwave equation will not be justified. Actually the problem is even much worse: in the HP transformation we assumed that there is long-range antiferromagnetic.
PDF Spin Nernst Effect of Magnons in Collinear Antiferromagnets.
Dec 15, 2010 · I'm working on spin-wave theory and I have a problem with a bogoliubov transformation. I must do the transformation with 3 bosons and i have no idea how to do it. I've only found the transformation for 1 and 2-mode bosons, but not for three. The special mathematical techniques introduced for \(S = \frac{1}{2}\) chains, namely the Bethe Ansatz for Heisenberg coupling and the Jordan-Wigner transformation for the XY-model, do not work for higher S or higher dimensions. Spin-wave theory is a much more general method of studying spin-models introduced by Anderson (1952) [] for ferromagnets and later applied by Oguchi (1963) [] to.
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