Abstract: An oxide superconductor having a composition of the formula: A.sub.n+1 Cu.sub.n O.sub.2n+1+.delta. in which A is at least one alkaline earth metal element selected from the group consisting of calcium, strontium and barium, n is an integer of at least one, and .delta. is a number larger than 0 and not larger than 1, a laminate structure in which a layer having a partial composition of A.sub.2 O.sub.1+.delta. and a layer having a partial composition of A.sub.n-1 Cu.sub.n O.sub.2n are alternately laminated, and a superconductive critical temperature equal to or higher than the liquid nitrogen temperature.

Abstract: A magnetoresistance effect element is provided which comprises a substrate on which a first magnetic layer having a thickness of 0.2 to 5 nm which contains cobalt, a second magnetic layer having a thickness of not larger than 5 nm which contains iron or nickel or an alloy thereof, a third magnetic layer having a thickness of 0.2 to 5 nm which contains cobalt and a nonmagnetic layer having a thickness of 0.5 to 5 nm are laminated in this order at least twice, wherein the thickness of the second magnetic layer is not larger than half of the total thickness of the first and third magnetic layers. The element is useful as a magnetoresistance sensor or head.