Abstract: A thin-film magnetic head in which the end face of a magnetic film protrudes beyond a substrate within the air bearing surface of the magnetic head. The magnetic film being made of a material containing a metallic element which is lap polished with abrasive grains containing the hydroxide of the metallic element. Because the air bearing surface is constructed according to the above procedure, the bit length of a magnetic disk can be decreased to ensure a higher record density.

Abstract: This invention provides a lap capable of reducing the pole recession produced between the substrate and the magnetic film when the air-bearing surface of a thin-film magnetic head is lapped, a lapping liquor used for such lapping, and a thin-film magnetic head having its air-bearing surface lapped by using them. Lapping is carried out by using a lap made of a material having both a phase of tin and a phase of brass with a greater rigidity in supporting the abrasive grains than tin, and a lapping liquor prepared by mixing an anionic surfactant (15) and an ampholytic surfactant (16). According to the present invention, it is possible to reduce the pole recession in the thin-film magnetic heads and to accordingly shorten the recording bit length of the magnetic discs.