Abstract
We present results of high-resolution thermal-expansion and specific-heat measurements on single crystalline -O. We find clear evidence for two almost degenerate phase transitions associated with the formation of the dimerized state around 33 K: A sharp first-order transition at K slightly below the onset of a second-order transition at K. The latter is accompanied by pronounced spontaneous strains. Our results are consistent with a structural transformation at induced by the incipient spin-Peierls order parameter above
- Received 16 October 1997
DOI:https://doi.org/10.1103/PhysRevB.57.8466
©1998 American Physical Society