Abstract
Structural, magnetic, calorimetric, and transport studies have been made on a synthesized Tl(1212) system of Tl( (0≤x≤1). Based on x-ray Rietveld refinement data, the bond length between Pr and oxygen in the adjacent layers increases with increasing x, even though the tetragonal lattice parameters decrease with progressive Sr substitution. This may result in a lower degree of hybridization between extended Pr 4f and O 2pπ orbitals and a corresponding reduction of superexchange magnetic coupling strength among Pr moments. Indeed, the anomalously high Néel temperature (Pr) decreases from 8.0–8.2 K for x=0 to 3.6–4.2 K for x=1. The magnetic entropy associated with this antiferromagnetic Pr ordering is estimated from specific-heat data, in which a heavy-fermion-like contribution also prevails.
- Received 8 February 1994
DOI:https://doi.org/10.1103/PhysRevB.50.4092
©1994 American Physical Society