We discuss the thermal entanglement close to a quantum phase transition by
analyzing the concurrence for one dimensional models in the quantum Ising
universality class. We demonstrate that the entanglement sensitivity to thermal
and to quantum fluctuations obeys universal T=0--scaling behaviour. We
show that the entanglement, together with its criticality, exhibits a peculiar
universal crossover behaviour.Comment: 12 pages; 5 figures (eps). References added; to be published in
Europhysics Letter