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Spin-torque oscillator, sensor, magnetic field sensing system, and disk drive

A spin torque oscillation and sensor technology, applied in the fields of magnetic field controlled resistors, instruments, magnetic recording, etc., can solve the problems of dielectric breakdown, small output signal, etc.

Inactive Publication Date: 2012-12-05
HITACHI GLOBAL STORAGE TECH NETHERLANDS BV
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  • Abstract
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  • Application Information

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Problems solved by technology

[0006] STO sensors based on CPP-GMR sensors are able to operate at very high current densities due to the non-magnetic and conductive spacer layer between the reference layer and the free layer, but have very small output signal
STO sensors based on CPP-TMR sensors have significantly higher magnetoresistance, but are susceptible to dielectric breakdown of the tunnel barrier at high current densities

Method used

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  • Spin-torque oscillator, sensor, magnetic field sensing system, and disk drive
  • Spin-torque oscillator, sensor, magnetic field sensing system, and disk drive
  • Spin-torque oscillator, sensor, magnetic field sensing system, and disk drive

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Embodiment Construction

[0019] The three-terminal STO according to the invention has applications other than as a magnetic field sensor, but will be described in detail below as a magnetic recording disk drive read head.

[0020] Figure 1 to Figure 4 A conventional CPP magnetoresistive (MR) magnetic field sensing sensor and system is shown. figure 1 is a simplified diagram of a conventional magnetic recording hard drive. The disk drive includes a magnetic recording disk 12 and a rotary voice coil motor (VCM) actuator 14 supported on a disk drive housing or base 16 . Disk 12 has a center of rotation 13 and is rotated in direction 15 by a spindle motor (not shown) mounted to base 16 . The actuator 14 rotates about an axis 17 and includes a rigid actuator arm 18 . A substantially flexible suspension 20 includes a flexure element 23 and is attached to the end of the arm 18 . A head carrier or air bearing slider 22 is attached to a curved element 23 . A magnetic recording read / write head 24 is form...

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Abstract

A spin-torque oscillator (STO) has a single free ferromagnetic layer that forms part of both a giant magnetoresistance (GMR) structure with a nonmagnetic conductive spacer layer and a tunneling magnetoresistance (TMR) structure with a tunnel barrier layer. The STO has three electrical terminals that connect to electrical circuitry that provides a spin-torque excitation current through the conductive spacer layer and a lesser sense current through the tunnel barrier layer. When the STO is used as a magnetic field sensor, the excitation current causes the magnetization of the free layer to oscillate at a fixed base frequency in the absence of an external magnetic field. A detector coupled to the sense current detects shifts in the free layer magnetization oscillation frequency from the base frequency in response to external magnetic fields.

Description

technical field [0001] The present invention generally relates to a spin-torque oscillator (STO), and more particularly, to a magnetic field sensor and a sensing system using an STO sensor. Background technique [0002] One conventional magnetoresistive (MR) sensor used as a read head in magnetic recording disk drives is a "spin valve" sensor based on the giant magnetoresistance (GMR) effect. A GMR spin-valve sensor has a laminate comprising two ferromagnetic layers separated by a non-magnetic, electrically conductive spacer layer, essentially copper (Cu). One ferromagnetic layer adjacent to the spacer layer has a fixed magnetization direction, such as pinned by exchange coupling with the adjacent antiferromagnetic layer, and is called the reference layer. Another ferromagnetic layer adjacent to the spacer layer has its magnetization direction free to rotate in the presence of an external magnetic field and is called the free layer. When a sense current is applied to the s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B5/127G11B5/48
CPCH01L43/08H01F10/1936G11B5/3903G11B5/48H01F10/3254G11B5/127G01R33/1284G01R33/098H01F10/329G11B2005/0005H01F10/3286H10N50/10
Inventor P.M.布拉甘卡B.A.格尼J.A.凯廷
Owner HITACHI GLOBAL STORAGE TECH NETHERLANDS BV
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