Entanglement in the Majumdar-Ghosh model
R. W. Chhajlany1 , P. Tomczak1 , A. Wójcik1 , J. Richter2
1 Physics Department, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
2 Institut für Theoretische Physik, Universität Magdeburg, P.O. Box 4120, D-39016 Magdeburg, Germany
Physical Review A, 75, 032340 (2007)
We present an analysis of the entanglement characteristics in the Majumdar-Ghosh (MG) or J1-J2 Heisenberg model. For a system consisting of up to 28 spins, there is a deviation from the scaling behaviour of the entanglement entropy characterizing the unfrustrated Heisenberg chain as soon as J2 > 0.25. This feature can be used as an indicator of the dimer phase transition that occurs at J2 = J2* = 0.2411 J1. Additionally, we also consider entanglement at the MG point J2=0.5 J1.