Abstract
We have observed two length scales in a crystal above the phase transition. A sharp Lorentzian profile in the critical diffuse scattering was superimposed on a broader one for a low-energy x-ray experiment in reflection, while no sharp component appeared in transmission at high energy. For the sharp component, we extracted tricritical exponents and at small reduced temperatures , where fluctuations are coherent over large distances. For larger , where the correlation length is comparable to an effective defect size, there is a crossover to altered exponents.
- Received 3 June 1998
DOI:https://doi.org/10.1103/PhysRevLett.81.2276
©1998 American Physical Society