Abstract
In the system , as x and p (the [ charge) are increased, the superconducting transition temperature first increases, then peaks becoming nonsuperconducting for x≳0.26. We report here a search for changes in physical properties at the values of x where is observed to change its behavior. The in-plane lattice constants and the normal resistivity both show a continued monotonic decrease over this entire region, suggesting that no major electronic changes occur. The tetragonal-to-orthorhombic transition temperature also decreases with increasing x and becomes unobservable for x≳0.19, suggesting that this structural transition itself is unrelated to the disappearance of superconductivity that occurs at higher doping levels. The magnetic spin susceptibility ) generally rises gradually with increasing doping (reflecting decreasing spin-spin interactions), reaches a maximum near x∼0.25, and then decreases. There is a weak peak in ) as a function of temperature at T=. As a function of increasing x, falls to zero near x∼0.25. These two observations might be related to the disappearance of superconductivity, since all three occur near the same value of Sr content x.
- Received 10 May 1989
DOI:https://doi.org/10.1103/PhysRevB.40.8872
©1989 American Physical Society