Abstract: The present invention provides a compound magnetoresistive material having a perovskite related structure and being represented by M1.sub.m M2.sub.n+1 M3.sub.n Z.sub.y, where: M1 is a first metal comprising at least one element selected from the group consisting of Tl, Bi, Pb, and Hg; M2 is a second metal comprising at least one element selected from the group consisting of alkaline earth metals; M3 is a third metal comprising at least one element selected from the group consisting of Mn, Os, and Ru; Z is one selected from the group consisting of oxygen and anions in which some oxygen elements are replaced by Oh, F, B, Cl, Br, S, Se and Te; m is equal to 1 or 2; 1.ltoreq.n.ltoreq.4; y is variable and depends upon a kind of elements constituting the perovskite related structure, a ratio of composition thereof, and synthesis conditions thereof.

Abstract: A magnetometric sensor has a wide p-portion formed of almost perfectly spin-polarized material, a wide d-portion also formed of almost perfectly spin-polarized material different in coercive force and a narrow n-portion provided between the wide p-portion and the wide d-portion formed of the almost perfectly spin-polarized material or non-magnetic material, and one of the p-portion and the d-portion changes the spin axes of the conduction electrons in the opposite direction to the other in the presence of a magnetic field for providing a potential gap between the Fermi surface of the p-portion and the Fermi surface of the d-portion, thereby causing electric current to change the amount thereof.

Abstract: An oxide superconducting material having a composition represented by a formulaTlSr.sub.2 (Sr.sub.n-x Y.sub.x)Cu.sub.n+1 O.sub.5+2nwherein n=1 or 2 and 0.1.ltoreq.x.ltoreq.n is provided. This material has a high critical current density Jc even by sintering at a relatively low temperature of 850.degree.-880.degree. C.