Hall effect and substitution effect in Pb 2Sr 2Y 1−xCa xCu 3O 8+δ

Abstract

The Hall effect of ceramic samples of Pb 2Sr 2Y 1−xCa xCu 3O 8 has been investigated for 0 ≦ x ≦ 0.5. The Hall coefficient R H is positive and decreases with increasing x, which is explained within the doped Mott-Hubbard model. For x < 0.1, R H increases with decreasing temperature like a conventional semiconductor. For x= 0.1, R H is almost constant. For 0.2 ≦ x ≦ 0.5, where T c appears, R H increases with decreasing temperature again, and 1/R He is expressed as αT + β (α > 0, β > 0). The temperature coefficient α increases with increasing T c. These temperature dependences of R H are common to high-T c oxides. Effects of the partial substitution of Fe, Co, Ni, Zn, Ga for Cu on T c have been also studied for x = 0.5. The decrease in T c is marked in order of Ga, Co, Zn, Ni, Fe. This is discussed in relation to experimental results on YBa 2Cu 3O 7.