# US 6,721,132 B2 · Inductive head and magnetic disk apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,721,132 B2 - Document ID: US6721132B2 - Status: Granted - Kind: B2 - Application number: 09/811,437 - Filed: 2001-03-20 - Published: 2002-02-14 - Granted: 2004-04-13 - Earliest claimed: 2000-07-24 - Assignees: Hitachi, Ltd. - Inventors: Shunichi Narumi; Hiroyuki Hoshiya; Yohji Maruyama - Web page: https://patentgrep.com/patent/US6721132B2 ## CPC - G11B 5/312: {for reducing flux leakage between the electrical coil layers and the magnetic cores or poles or between the magnetic cores or poles} - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - G11B 5/3116: {Shaping of layers, poles or gaps for improving the form of the electrical signal transduced, e.g. for shielding, contour effect, equalizing, side flux fringing, cross talk reduction between heads or between heads and information tracks (G11B5/3113, G11B5/245 take precedence)} - G11B 5/3967: {Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read (G11B5/3906 takes precedence)} - Y10S 977/724: Devices having flexible or movable element - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract In an inductive head according to the present invention, in order to efficiently carry a magnetic flux to a magnetic pole tip layer, the top surface of the rear end of the magnetic pole tip layer is etched away so as to connect the rear end of the magnetic pole tip layer to the front end of an upper magnetic core having a width larger than that of the rear end of the magnetic pole tip layer. It is possible to realize a recording head having a large recording magnetic field. In addition, the front end of the upper magnetic core is recessed from an air bearing surface by 0.2 to 3.0 μm so as to reduce the magnetic field leaked from the end of the upper magnetic core. ## Claims ### Claim 1 An inductive head comprising a lower magnetic core formed on a substrate, a magnetic pole tip layer formed on the lower magnetic core, an upper magnetic core coupled in its front end to the magnetic pole tip layer, coupled in its rear end to the lower magnetic core, having a width of the front end smaller than that of the rear end, and having at least partially a shape gradually reducing the width from the rear end to the front end, coils disposed between the upper magnetic core and the lower magnetic core, and an insulating layer formed between the coils and the upper magnetic core or the lower magnetic core, wherein the distance between a top surface of the magnetic pole tip layer and an under surface of magnetic pole tip layer in a rear end region away from an air bearing surface in a region connecting the magnetic pole tip layer to said upper magnetic core is shorter than the distance between the top surface of said magnetic pole tip layer in the air bearing surface and the under surface of magnetic pole tip layer, and said magnetic pole tip layer consists of three layers of a magnetic layer/magnetic gap layer/magnetic layer. ### Claim 2 (depends on 1) The inductive head according to claim 1, comprising a magnetic gap layer formed at least near the air bearing surface on said lower magnetic core, a non-magnetic layer for maintaining a thickness increased with moving away from the air bearing surface, in a region such that the magnetic gap layer is moved away from the air bearing surface, or in a region such that the magnetic gap layer is moved away from the air bearing surface and in a region such that the lower core is moved away from the air bearing surface, and said magnetic pole tip layer formed on the non-magnetic layer. ### Claim 3 (depends on 2) The inductive head according to claim 2, wherein said magnetic pole tip layer is formed on the lower magnetic core near the air bearing surface, and is formed on the non-magnetic layer in the region away from the air bearing surface. ### Claim 4 (depends on 1) The inductive head according to claim 1, wherein the front end of said upper magnetic core is recessed from the air bearing surface by 0.2 to 3.0 μm. ### Claim 5 (depends on 1) The inductive head according to claim 1, wherein the saturation magnetic flux density of the magnetic pole tip layer is higher than that of any one of the upper magnetic core and the lower magnetic core. ### Claim 6 A magnetic head comprising: a lower magnetic core, a magnetic pole tip layer formed on the lower magnetic core, where the magnetic pole tip layer consists of three layers of a magnetic layer/magnetic gap layer/magnetic layer, an upper magnetic core coupled in a front end to said magnetic pole tip layer, and in a rear end to said lower magnetic core, a coil formed between said upper magnetic core and said lower magnetic core, and an insulating layer, wherein a thickness of a front end of said magnetic pole tip layer which includes thicknesses of all three layers of the magnetic layer/magnetic gap layer/magnetic layer is thicker than a thickness of a rear end of said magnetic pole tip layer which includes thicknesses of all three layers of the magnetic layer/magnetic gap layer/magnetic layer, and a width in a track width direction of said front end of said upper magnetic core is bigger than a width in a track width direction of said rear end of said magnetic pole tip layer. ### Claim 7 (depends on 6) A magnetic head according to claim 6, wherein said magnetic pole tip layer comprises three layer of magnetic layer/non-magnetic layer/magnetic layer. ### Claim 8 (depends on 6) A magnetic head according to claim 6, wherein said front end of said upper magnetic core is recessed from the air bearing lifting surface by 0.2 to 0.3 μm. ### Claim 9 An inductive head comprising a lower magnetic core formed on a substrate, a magnetic pole tip layer formed on the lower magnetic core which consists of three layers of a magnetic layer/magnetic gap layer/magnetic layer, an upper magnetic core coupled in its front end to the magnetic pole tip layer, coupled in its rear end to the lower magnetic core, having a width of the front end smaller than that of the rear end, and having at least partially a shape gradually reducing the width from the rear end to the front end, coils disposed between the upper magnetic core and the lower magnetic core, and an insulating layer formed between the coils and the upper magnetic core or the lower magnetic core, wherein a distance between a top surface of the magnetic pole tip layer and an under surface of magnetic pole tip layer which includes thicknesses of all three layers of the magnetic layer/magnetic gap layer/magnetic layer in a line substantially normal to the lower magnetic core and in a rear end region away from an air bearing surface in a region connecting the magnetic pole tip layer to said upper magnetic core, is shorter than the distance in the air bearing surface between the top surface of said magnetic pole tip layer and the under surface of magnetic pole tip layer which includes thicknesses of all three layers of the magnetic layer/magnetic gap layer/magnetic layer in a line substantially normal to the lower magnetic core. ### Claim 10 (depends on 9) The inductive head according to claim 9, comprising a magnetic gap layer formed at least near the air bearing surface on said lower magnetic core, a non-magnetic layer for maintaining a thickness increased with moving away from the air bearing surface, in a region such that the magnetic gap layer is moved away from the air bearing surface, or in a region such that the magnetic gap layer is moved away from the air bearing surface and in a region such that the lower core is moved away from the air bearing surface, and said magnetic pole tip layer formed on the non-magnetic layer. ### Claim 11 (depends on 10) The inductive head according to claim 10, wherein said magnetic pole tip layer is formed on the lower magnetic core near the air bearing surface, and is formed on the non-magnetic layer in the region away from the air bearing surface. ### Claim 12 (depends on 9) The inductive head according to claim 9, wherein the front end of said upper magnetic core is recessed from the air bearing surface by 0.2 to 3.0 μm. ### Claim 13 (depends on 9) The inductive head according to claim 9, wherein the saturation magnetic flux density of the magnetic pole tip layer is higher than that of any one of the upper magnetic core and the lower magnetic core.