The stripe-like collective excitation in cuprates: A variational Monte-Carlo study

C. S. Ting, Hongyi Chen, T. K. Lee

Fei Tan, Qiang-Hua Wang

Ting-Kuo Lee, Chung-Pin Chou

Zuodong Yu, Yuan Zhou, Chang-De Gong

The hour-glass-like dispersion of spin excitations is a common feature of underdoped cuprates. It was qualitatively explained by the random-phase approximation based on various ordered states with some phenomenological parameters; however, its origin remains elusive. Here, we present a numerical study of spin dynamics in the $t\text{\ensuremath{-}}J$ model using the variational Monte Carlo method. This parameter-free method satisfies the no double-occupancy constraint of the model and thus provides a better evaluation on the spin dynamics with respect to various mean-field trial states. We conclude that the lower branch of the hour-glass dispersion is a collective mode and the upper branch more than the other candidates is likely the consequence of the stripe state.

Valentin Stanev, Zachary M. Raines, Victor M. Galitski

Kota Ido, Takahiro Ohgoe, Masatoshi Imada

We study competitions among charge-uniform and -inhomogeneous states in two-dimensional Hubbard models by using a variational Monte Carlo method. At realistic parameters for cuprate superconductors, emergent effective attraction of carriers generated from repulsive Coulomb interaction leads to charge/spin stripe ground states, which severely compete with uniform superconducting excited states in the energy scale of 10 K for cuprates. Stripe period increases with decreasing hole doping $\ensuremath{\delta}$, which agrees with the experiments for La-based cuprates at $\ensuremath{\delta}=1/8$. For lower $\ensuremath{\delta}$, we find a phase separation. Implications of the emergent attraction for cuprates are discussed.