Patent application number | Description | Published |
20100328799 | Spin Torque Oscillator Sensor - A spin torque oscillation magnetoresistive sensor for measuring a magnetic field. The sensor uses a change in precessional oscillation frequency of a magnetization of a magnetic layer to determine the magnitude of a magnetic field. The sensor can include a magnetic free layer, a magnetic pinned layer and a non-magnetic layer sandwiched therebetween. Circuitry is connected with these layers to induce an electrical current through the layers. Spin polarization of electrons traveling through the device causes a spin torque induced precession of the magnetization of one or more of the layers. The frequency of this oscillation modulates in response to a magnetic field. The modulation of the oscillation frequency can be measured to detect the presence of the magnetic field, and determine its magnitude. | 12-30-2010 |
20120307404 | THREE-TERMINAL SPIN-TORQUE OSCILLATOR (STO) - 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. | 12-06-2012 |
20130009712 | SPIN-TORQUE OSCILLATOR (STO) WITH MAGNETICALLY DAMPED FREE LAYER - A spin-torque oscillator (STO) has increased magnetic damping of the oscillating free ferromagnetic layer. The Gilbert magnetic damping parameter (a) is at least 0.05, and preferably greater than 0.05. The free layer may be a any type of conventional ferromagnetic material, but contains one or more damping elements as a dopant. The damping element is selected from the group consisting of Pt, Pd and the 15 lanthanide elements. The free layer damping may also be increased by a damping layer adjacent the free layer. One type of damping layer may be an antiferromagnetic material, like a Mn alloy. As a modification to the antiferromagnetic damping layer, a bilayer damping layer may be formed of the antiferromagnetic layer and a nonmagnetic metal electrically conductive separation layer between the free layer and the antiferromagnetic layer. Another type of damping layer may be one formed of one or more of the elements selected from Pt, Pd and the lanthanides. | 01-10-2013 |
20130063841 | THERMAGNONIC SPIN-TORQUE OSCILLATOR(STO) AND SENSOR UTILIZING SAME TO DETECT SHIFTS IN THE FREE LAYER MAGNETIZATION OSCILLATION FREQUENCY - A “thermagnonic” spin-torque oscillator (STO) uses heat flow alone to cause the spin-torque (ST) effect and generate the persistent oscillation of the free layer magnetization. In addition to the conventional free and reference layers, the thermagnonic STO also includes a magnetic oxide layer having a fixed in-plane magnetization, a ferromagnetic metallic layer on one surface of the magnetic oxide layer, a nonmagnetic electrically conductive layer between the free layer and the metallic layer, and an electrically resistive heater on the other surface of the magnetic oxide layer. Due to the thermagnonic effect, heat flow from the magnetic oxide layer through the metallic layer, conductive layer and free layer ultimately results in a spin transfer torque (STT) to the free layer. Electrical sense current flowing in the opposite direction as the heat flow is used to monitor the frequency of oscillation of the free layer magnetization. | 03-14-2013 |
20130148223 | IMPLEMENTING SPIN-TORQUE OSCILLATOR SENSING WITH ENHANCED DEMODULATOR FOR HARD DISK DRIVES - A method, apparatus, and system are provided for implementing spin-torque oscillator (STO) sensing with a demodulator for hard disk drives. The demodulator measures an instantaneous phase of the readback signal from a STO sensor and converts the readback signal into a signal that is proportional to the magnetic field affecting the STO frequency during a bit time. The converted signal is used for processing by conventional data detection electronics. | 06-13-2013 |
20130148224 | IMPLEMENTING SPIN-TORQUE OSCILLATOR SENSING WITH ENHANCED INTEGRATED DEMODULATOR FOR HARD DISK DRIVES - A method, apparatus, and system are provided for implementing spin-torque oscillator sensing with an enhanced integrated demodulator for hard disk drives. The demodulator receives an input signal from a STO read sensor having an oscillation frequency ω related to the strength of the detected magnetic signal field. The demodulator includes a pair of mixers coupled to a quadrature reference oscillator with respective quadrature components cos(ω | 06-13-2013 |
20130148229 | IMPLEMENTING SPIN-TORQUE OSCILLATOR SENSING WITH ENHANCED DELAY CONTROL FEEDBACK CIRCUIT FOR HARD DISK DRIVES - A method, apparatus, and system for implementing spin-torque oscillator (STO) sensing with an enhanced delay control feedback circuit for hard disk drives. A detector receives an input signal from a STO read sensor having an oscillation frequency related to the strength of the detected magnetic signal field. The received input signal is mixed with a time delayed input signal for providing a detector output signal. A low frequency component signal of the detector output signal is monitored and a delay control feedback is applied to an adjustable time delay to bias the DC signal of the detector output signal. | 06-13-2013 |
20130222949 | SPIN-TORQUE OSCILLATOR (STO) WITH ANTIPARALLEL-COUPLED FREE FERROMAGNETIC LAYERS AND MAGNETIC DAMPING - A spin-torque oscillator with antiferromagnetically-coupled free layers has at least one of the free layers with increased magnetic damping. The Gilbert magnetic damping parameter (α) is at least 0.05. The damped free layer may contain as a dopant one or more damping elements selected from the group consisting of Pt, Pd and the 15 lanthanide elements. The free layer damping may also be increased by a damping layer adjacent the free layer. One type of damping layer may be an antiferromagnetic material, like a Mn alloy. As a modification to the antiferromagnetic damping layer, a bilayer damping layer may be formed of the antiferromagnetic layer and a nonmagnetic metal electrically conductive separation layer between the free layer and the antiferromagnetic layer. Another type of damping layer may be one formed of one or more of the elements selected from Pt, Pd and the lanthanides. | 08-29-2013 |
20140291283 | METHOD FOR MAKING A CURRENT-PERPENDICULAR-TO-THE-PLANE (CPP) MAGNETORESISTIVE (MR) SENSOR WITH REDUCED-WIDTH SELF-ALIGNED TOP ELECTRODE - A method for making a current-perpendicular-to-the-plane magnetoresistive sensor structure produces a top electrode that is “self-aligned” on the top of the sensor and with a width less than the sensor trackwidth. A pair of walls of ion-milling resistant material are fabricated to a predetermined height above the biasing layers at the sensor side edges. A layer of electrode material is then deposited onto the top of the sensor between the two walls. The walls serve as a mask during angled ion milling to remove outer portions of the electrode layer. The height of the walls and the angle of ion milling determines the width of the resulting top electrode. This leaves the reduced-width top electrode located on the sensor. Because of the directional ion milling using walls that are aligned with the sensor side edges, the reduced-width top electrode is self-aligned in the center of the sensor. | 10-02-2014 |
20140340791 | CURRENT-PERPENDICULAR-TO-THE-PLANE (CPP) MAGNETORESISTIVE SENSOR WITH REDUCED-WIDTH TOP AND BOTTOM ELECTRODES AND METHOD FOR MAKING - A current-perpendicular-to-the plane magnetoresistive sensor has top and bottom electrodes narrower than the sensor trackwidth. The electrodes are formed of one of Cu, Au, Ag and AgSn, which have an ion milling etch rate much higher than the etch rates for the sensor's ferromagnetic materials. Ion milling is performed at a high angle relative to a line orthogonal to the plane of the electrode layers and the layers in the sensor stack. Because of the much higher etch rate of the material of the top and bottom electrode layers, the electrode layers will have side edges that are recessed from the side edges of the free layer. This reduces the surface areas for the top and bottom electrodes, which causes the sense current passing through the sensor's free layer to be confined in a narrower channel, which is equivalent to having a sensor with narrower physical trackwidth. | 11-20-2014 |