Quantum entanglement and quantum phase transitions in frustrated spin ladder with ferromagnetic interchain exchanges

Using the density matrix renormalization group technique, the quantum phase transitions in a frustrated spin-1/2 ladder with ferromagnetic interchain exchanges are investigated. According to our results, the two-rung entanglement is capable of describing the quantum phase transitions. Furthermore, its first order derivative is shown to be more sensitive than order parameters for determining phase boundary. Therefore, the intermediate columnar dimerized phase region is determined definitely.