Observation of Pr and Gd ordering in the 2212-type compounds (Pb0.5Cu0.5

Abstract

Magnetic and calorimetric measurements have been made to reveal a Pr ordering in the (Pb05Cuo, )2{Bao, Sro, )&PrCu20g compound which has the {Pb,Cu)-2212-type tetragonal structure with 0 0 lattice parameters a = 3.878(3) A and c =27.594(9) A. The transition occurs at a relatively high Tz{Pr } of 9 K. In comparison, isostructural (Pbo 5Cuo &)2 (Bao 5Sro 5)2GdCu&O, exhibits a T&{od) of only 2.2 K.The magnetic entropy associated with the Pr ordering has a lower limit value equivalent to about 20% of Rln3 expected for Pr + with a quasitriplet ground state, suggesting a more three-dimensional-like process. These results represent the observation of anomalous Pr ordering in the 2212-type cuprate and a complete demonstration of such effects in all two-Cu02-layer m 212 (m = 1,2,3) systems.

Anomalous Pr Ordering for Pr 1222- and 2222-Type Structure Compounds

“…So far, the Tl-1212 type Tl(Ba,Sr) 2 PrCu 2 O 7 , (Pb,Cu)-1212 type (Pb,Cu)Sr 2 PrCu 2 O 7 , Hg-1212 type HgSr 2 PrCu 2 O 7 , Nb-1212 type NbBa 2 PrCu 2 O 7 , and Cu-123 type Pr(Ba,R) 2 Cu 3 O 7 (R ¼ La, Pr) nonsuperconducting compounds also exhibit the common feature of having anomalous T N (Pr) values ranging from 2 to 17 K [7][8][9][10][11][12][13][14][15][16][17][18]. Other 2212-type compounds with T N (Pr) of 9 K for (Pb,Cu)-2212 (Pb 0.5 Cu 0.5 ) 2 (Ba 0.5 Sr 0.5 ) 2 PrCu 2 O 8 and 17 K for Cu-2212 PrBa 2 Cu 4 O 8 , and another 3212-type compound, with T N (Pr) of 6-14 K for (Pb,Cu)-3212 (Pb 2 Cu)(Ba,Sr) 2 PrCu 2 O 8 were also observed [19][20][21][22] [25][26][27]. Hence, this seems to suggest that a correlation exists between the suppression of superconductivity and anomalous Pr magnetism in high-T c cuprates.…”

Growth of Bi2Sr2Ca1−xPrxCu2Oy single crystals by traveling solvent floating zone method

“…Identifying the role of each constituent in superconducting compounds provides an indirect route of recognizing the origin of superconductivity. Among them, cation substitution of Ca in Bi-2212 compound has been studied extensively [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. For example, it has been reported that the superconducting temperature of Bi-2212 was reduced by replacing Ca with other rare earth elements, such as Gd 3+ [4,5], Ce 3+ [6] and La 3+ [7,8].…”

“…For example, it has been reported that the superconducting temperature of Bi-2212 was reduced by replacing Ca with other rare earth elements, such as Gd 3+ [4,5], Ce 3+ [6] and La 3+ [7,8]. In particular, the Pr-substituted cuprate was found to show some anomalies on its antiferromagnetic transition temperature [9][10][11]. The real cause for such phenomenon has not been clearly identified because most of the polycrystalline Pr-doped Bi-2212 samples used in the studies are often found to be inhomogeneous [12][13][14][15][16].…”