In this story of TiSe2, experiment and theory meet to provide an explanation for a long-standing enigma. In this system, the electrons rearrange themselves spontaneously at low temperature, resulting in a new periodicity from that of the original lattice. This phase change is driven by a decrease in the total energy of the system. However, the nature of this transition has been a matter of controversy for a long time. Recently, physicists from Neuchâtel rejuvenated an old theory to explain their photoemission data taken at the SLS on TiSe2 and to provide a promising solution to this problem.
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Facility: SLS
Evidence for an Excitonic Insulator Phase in 1T-TiSe2, H. Cercellier, C. Monney, F. Clerc, C. Battaglia, L. Despont, M. G. Garnier, H. Beck, P. Aebi*, Luc Patthey, H. Berger and L. Forró , Phys. Rev. Lett. 99, 146403 (2007)
Evidence for an Excitonic Insulator Phase in 1T-TiSe2, H. Cercellier, C. Monney, F. Clerc, C. Battaglia, L. Despont, M. G. Garnier, H. Beck, P. Aebi*, Luc Patthey, H. Berger and L. Forró , Phys. Rev. Lett. 99, 146403 (2007)