  In the study of entanglement in a spin chain, people often consider the
nearest-neighbor spins. The motivation is the prevailing role of the short
range interactions in creating quantum correlation between the 1st neighbor
(1N) spins. Here, we address the same question between farther neighbor spins.
  We consider the one-dimensional (1D) spin-1/2 XY model in a magnetic field.
Using the fermionization approach, we diagonalize the Hamiltonian of the
system. Then, we provide the analytical results for entanglement between the
2nd, 3rd and 4th neighbor (denoted as 2N, 3N, and 4N respectively) spins. We
find a magnetic entanglement that starts from a critical entangled-field
($h_c^{E}$) at zero temperature. The critical entangled-field depends on the
distance between the spins. In addition to the analytical results, the
mentioned phenomenon is confirmed by the numerical Lanczos calculations. By
adding the temperature to the model, the magnetic entanglement remains stable
up to a critical temperature, $T_c$. Our results show that entanglement spreads
step by step to farther neighbors in the spin chain by reducing temperature. At
first, the 1N spins are entangled and then further neighbors will be entangled
respectively. $T_c$ depends on the value of the magnetic field and will be
maximized at the quantum critical field.
