# US 9,437,218 B2 · Magnetic recording head and magnetic recording apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,218 B2 - Document ID: US9437218B2 - Status: Granted - Kind: B2 - Application number: 14/796,462 - Filed: 2015-07-10 - Published: 2016-01-28 - Granted: 2016-09-06 - Earliest claimed: 2014-07-25 - Assignees: Kabushiki Kaisha Toshiba - Applicants: Kabushiki Kaisha Toshiba - Inventors: Kiwamu Kudo; Hirofumi Suto; Tazumi Nagasawa; Koichi Mizushima; Rie Sato - Web page: https://patentgrep.com/patent/US9437218B2 ## CPC - G11B 5/00: Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor (G11B11/00 {and G11B13/00} take precedence) - G11B 5/235: Selection of material for gap filler {(G11B5/232 takes precedence)} - G11B 5/3146: {magnetic layers} - G11B 2005/0002: {Special dispositions or recording techniques} - G11B 2005/0021: {Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal} - G11B 2005/0024: {Microwave assisted recording} - G11B 2005/3996: {large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices} - 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) ## Abstract According to an embodiment, a magnetic recording head includes a main magnetic pole and a spin torque oscillator. The spin torque oscillator includes a first perpendicular free layer, a second perpendicular free layer, and a first spacer layer, each of the first perpendicular free layer and the second perpendicular free layer including a magnetic anisotropy axis in a direction perpendicular to a film plane of the spin torque oscillator. An effective perpendicular magnetic anisotropy magnetic field of the first perpendicular free layer is smaller than an effective perpendicular magnetic anisotropy magnetic field of the second perpendicular free layer, and a current is applied from the first perpendicular free layer side to the second perpendicular free layer side. ## Claims ### Claim 1 A magnetic recording head comprising: a main magnetic pole which generates a recording magnetic field; and a spin torque oscillator which generates a high frequency magnetic field, the spin torque oscillator comprising a pair of electrode layers and a multilayer film provided between the pair of electrode layers, the multilayer film comprising a first perpendicular free layer in which magnetization is rotatable, a second perpendicular free layer in which magnetization is rotatable, and a first spacer layer provided between the first perpendicular free layer and the second perpendicular free layer, each of the first perpendicular free layer and the second perpendicular free layer including a magnetic anisotropy axis in a direction perpendicular to a film plane of the spin torque oscillator, wherein an effective perpendicular magnetic anisotropy magnetic field of the first perpendicular free layer is smaller than an effective perpendicular magnetic anisotropy magnetic field of the second perpendicular free layer, and a current is applied from the first perpendicular free layer side to the second perpendicular free layer side through the pair of electrode layers. ### Claim 2 (depends on 1) The magnetic recording head according to claim 1, wherein the multilayer film further comprises a third perpendicular free layer which includes a magnetic anisotropy axis in the direction perpendicular to the film plane of the spin torque oscillator and in which magnetization is rotatable, and a second spacer layer provided between the second perpendicular free layer and the third perpendicular free layer, the second perpendicular free layer being provided between the first perpendicular free layer and the third perpendicular free layer, the effective perpendicular magnetic anisotropy magnetic field of the second perpendicular free layer is smaller than an effective perpendicular magnetic anisotropy magnetic field of the third perpendicular free layer, and a current is applied from the first perpendicular free layer side to the third perpendicular free layer side through the pair of electrode layers. ### Claim 3 (depends on 2) The magnetic recording head according to claim 2, wherein the third perpendicular free layer comprises at least one of a CoCr system material, a Co/Pd multilayer film, a Co/Ni multilayer film, a Co/Pt multilayer film, an L10 alloy, Co3Pt, SmCo, a CoFe/MgO interface, a CoFeB/MgO interface, and a FeB/MgO interface. ### Claim 4 (depends on 1) The magnetic recording head according to claim 1, wherein the first perpendicular free layer comprises at least one of a CoCr system material, a Co/Pd multilayer film, a Co/Ni multilayer film, a Co/Pt multilayer film, an L10 alloy, Co3Pt, SmCo, a CoFe/MgO interface, a CoFeB/MgO interface, and a FeB/MgO interface. ### Claim 5 (depends on 1) The magnetic recording head according to claim 1, wherein the second perpendicular free layer comprises at least one of a CoCr system material, a Co/Pd multilayer film, a Co/Ni multilayer film, a Co/Pt multilayer film, an L10 alloy, Co3Pt, SmCo, a CoFe/MgO interface, a CoFeB/MgO interface, and a FeB/MgO interface. ### Claim 6 (depends on 1) A magnetic recording apparatus comprising: a magnetic recording medium; a magnetic head including a magnetic reproducing head, and the magnetic recording head according to claim 1; a driving mechanism which moves the magnetic head and the magnetic recording medium relative to each other; and a signal processor which carries out writing of a signal to the magnetic recording medium by using the magnetic recording head, and reading of a signal from the magnetic recording medium by using the magnetic reproducing head. ### Claim 7 (depends on 6) The magnetic recording apparatus according to claim 6, wherein the magnetic reproducing head comprises another spin torque oscillator including at least one free layer in which magnetization is rotatable, and the signal processor reproduces the magnetic information of the magnetic recording medium by detecting a change in amplitude or phase of the high frequency output of the spin torque oscillator of the magnetic reproducing head. ### Claim 8 (depends on 6) The magnetic recording apparatus according to claim 6, wherein the magnetic recording medium is a three-dimensional recording medium including a plurality of recording layers.