Type of Document Dissertation Author Kar, Satyaki Author's Email Address firstname.lastname@example.org URN etd-07092010-134517 Title Role of Phonons, Doping and Domain Walls in Hole Propagation in Two-Dimensional Quantum Antiferromagnets Degree Doctor of Philosophy Department Physics, Department of Advisory Committee
Advisor Name Title Efstratios Manousakis Committee Chair David Van Winkle Committee Member Pedro Schlottmann Committee Member Peter Hoeflich Committee Member Eric Hellstrom University Representative Keywords
- Spin Wave
- t-J Model
Date of Defense 2010-06-24 Availability unrestricted AbstractWe study the two-dimensional (2D) t−J model (and its extensions) in order to understand
the hole dynamics in the 2D CuO2 plane of the cuprate superconductors. Within the linear
spin wave approximation (LSW) of the Hamiltonian and the non-crossing approximation
(NCA) for the hole self energies, thermal broadening of the hole spectral peaks is investigated
with and without the contribution of optical phonons. We find the string excitations 
to survive even for relatively strong electron-phonon coupling. Experimental angle-resolved
photoemission spectroscopy (ARPES) results compare well with our calculations at finite
temperature when we use strong electron-phonon coupling („). With vertex correction the
agreement with experiment becomes possible even at a moderate value of „.
Finite hole doping in a 2D t−J model and its extensions at T = 0 is studied using NCA.
Dressed hole and magnon Greenís functions are obtained to analyze the hole energy bands/
Fermi surface topology and the magnon broadening and softening for the doped system.
The doping-dependent staggered magnetization of the system is computed and the doping
fraction up to which the staggered magnetization is non-zero is indicated. Contribution of
the anomalous magnons has been reported as well.
We also study the dynamics of a hole in a 2D lattice in a stripe-ordered background.
Within the same LSW and NCA treatment to the t − J Hamiltonian we obtain the different
spin wave modes and hole Greenís functions of the superlattice structure. The hole spectra
indicates the preference for the hole to be in the anti-phase domain wall rather than being
within the antiferromagnetic block.
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