Spin-wave theory for dimerized ferromagnetic chains
نویسندگان
چکیده
We describe a Peierls dimerization which occurs in ferromagnetic spin chains at finite temperature, within the modified spin-wave theory. Usual spin-wave theory is modified by introducing a Lagrange multiplier which enforces a nonmagnetic state at finite temperature. It is shown that this method gives results in excellent agreement with the density–matrix renormalization group applied to transfer matrices for dimerized ferromagnetic chains. We study bond correlation functions 〈Si · Si+1〉 and explore the characteristic features of dimerization in the specific heat.
منابع مشابه
امواج اسپین و ناهمسانگردی تک جهتی در دولایه‌ایهای نازک فرومغناطیسپادفرومغناطیسی
In this paper a simple model calculation of spin wave is given for the ferromagtic layer in ultra thin ferromagnetic/antiferromagnetic bilayer. In this model the magnetic layer is assumed as an isolated layer but the effect of antiferromagnetic layer on ferromagnetic layer and unidirectional anisotropy, is given in the effective field applied on each spin. The thin layer is assumed as two-dim...
متن کاملGround-state factorization and quantum phase transition in dimerized spin chains
We study the occurrence of ground-state factorization in dimerized XY spin chains in a transverse field. Together with the usual ferromagnetic and antiferromagnetic regimes, a third case emerges, with no analogous in translationally invariant systems, consisting of an antiferromagnetic Neél-type ground state where pairs of spins represent the unitary cell. Then, we calculate the exact solution ...
متن کاملTrapped-ion quantum simulation of tunable-range Heisenberg chains
Quantum-optical techniques allow for generating controllable spin-spin interactions between ions, making trapped ions an ideal quantum simulator of Heisenberg chains. A single parameter, the detuning of the Raman coupling, allows to switch between ferromagnetic and antiferromagnetic chains, and to modify the range of the interactions. On the antiferromagnetic side, the system can be tuned from ...
متن کاملDimerized phase and transitions in a spatially anisotropic square lattice antiferromagnet.
We investigate the spatially anisotropic square lattice quantum antiferromagnet. The model describes isotropic spin-1/2 Heisenberg chains (exchange constant J) coupled antiferromagnetically in the transverse (J( perpendicular )) and diagonal (J(x)), with respect to the chain, directions. Classically, the model admits two ordered ground states-with antiferromagnetic and ferromagnetic interchain ...
متن کاملThermally activated Peierls dimerization in ferromagnetic spin chains.
We demonstrate that a Peierls dimerization can occur in ferromagnetic spin chains activated by thermal fluctuations. The dimer order parameter and entanglement measures are studied as functions of the modulation of the magnetic exchange interaction and temperature, using a spin-wave theory and the density-matrix renormalization group. We discuss the case where a periodic modulation is caused by...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2009