Structural and crystal field studies on a single crystal of PrBa2Cu3O7−δ

Anomalous Pr ordering inHgSr2PrCu2Chou1, Hsu2, Shieh3 et al. 1996Phys. Rev. B

“…[1][2][3][4][5][6] With further oxygen deficiency, T N ͑Pr͒ decreases to 10 K in tetragonal PrBa 2 Cu 3 O 6 . 5,7 In comparison, other magnetic rareearth compounds have a maximum T N (R) of 2.2 K in GdBa 2 Cu 3 O 7 . 8,9 Meanwhile, Pr substitution leads to T c suppression from above 90 K in (R 1Ϫx Pr x )Ba 2 Cu 3 O 7 .…”

Systematic variation of T N(Pr) for the two-CuO2-layer cuprate m212 (m=1, 2, 3) systems

“…For the oxygendepleted tetragonal 1236͑Ba͒ PrBa 2 Cu 3 O 6 ͑Cu-1212͒ compound, a single long Pr-O bond length of 2.472 Å with lower T N ͑Pr͒ of 10 K was observed. 7 Clearly, T N ͑Pr͒ decreases monotonically with increasing Pr-O bond length which reflects the degree of Pr 4 f -O 2p orbital hybridization or the strength of Pr-O-Pr superexchange coupling. Meanwhile, an effective coupling occurs between Cu and Pr moments through oxygen 2p /2p as revealed by preliminary neutron and nuclear magnetic resonance studies on Tl-1212 Tl͑Ba,Sr͒ 2 PrCu 2 O 7Ϫ␦ system.…”

“…[1][2][3][4][5][6] With further oxygen deficiency, T N decreases to 10 K in tetragonal PrBa 2 Cu 3 O 6 . 5,7 In comparison, other magnetic rare earth compounds have a maximum T N ͑R͒ of 2.2 K in GdBa 2 Cu 3 O 7 . 8,9 Since Pr is one of the lightest elements of rare-earth series, its 4 f wave function is more extended and the anomalously high T N observed indicates the importance of the quasi-two-dimensional ͑quasi-2D͒ Pr-O-Pr superexchange magnetic coupling through the strong hybridization between the Pr 4 f and the eight O 2 p orbitals in the adjacent two-CuO 2 layers.…”