The inventive concepts provide a magnetic property measurement apparatus capable of quickly measuring a magnetic property of a subject without a decrease in a measurement speed that might occur due to an electromagnet. In addition, the inventive concepts provide a magnetic property measurement apparatus capable of monitoring a magnetization distribution of a memory device as an image and integrating images by using a TDI camera, thereby being capable of performing highly sensitive measurement and not having to capture images for a long time. The magnetic property measurement apparatus includes: a magnetic field generation unit configured to generate a magnetic field which is constant with time and varies with relative position; a mobile unit configured to move a subject to be measured in the magnetic field; and a measurement unit configured to measure a magnetic property of the subject moving in the magnetic field.

In a method of testing a multilayer structure containing a magnetic layer, one or more network parameters are measured of a waveguide that is electromagnetically coupled with the multilayer structure as a function of frequency and as a function of a magnetic field applied to the multilayer structure during the measuring of the network parameters. Based on the measured one or more network parameters, at least one magnetic property of the magnetic layer of the multilayer structure is determined. The network parameters in some embodiments are S-parameters. The at least one magnetic property may include an effective anisotropy field of the magnetic layer and/or a damping constant of the magnetic layer.

A computer-implemented method to detect a damaged tunneling magnetoresistance (TMR) sensor includes applying current at at least two different current values to the TMR sensor and measuring a resistance, R.sub.TMR, at each current value. The method also includes measuring a slope in resistance vs. bias current, RD.sub.SLP, using the measured resistances R.sub.TMR and the at least two different current values. The method includes calculating a ΔRD.sub.SLP value as a difference between the RD.sub.SLP value and an expected value, RD.sub.SLP-expected, for the TMR sensor. The method includes determining whether the ΔRD.sub.SLP value is within a predefined range. In response to determining that the ΔRD.sub.SLP value is outside the predefined range, the method includes outputting an indication that the TMR sensor fails. In response to determining that the ΔRD.sub.SLP value is within the predefined range, the method includes outputting an indication that the TMR sensor passes.

A multilayer exchange spring recording media consists of a magnetically hard magnetic storage layer strongly exchange coupled to a softer nucleation host. The strong exchange coupling can be through a coupling layer or direct. The hard magnetic storage layer has a strong perpendicular anisotropy. The nucleation host consists of one or more ferromagnetic coupled layers. For a multilayer nucleation host the anisotropy increases from layer to layer. The anisotropy in the softest layer of the nucleation host can be two times smaller than that of the hard magnetic storage layer. The lateral exchange between the grains is small. The nucleation host decreases the coercive field significantly while keeping the energy barrier of the hard layer almost unchanged. The coercive field of the total structure depends on one over number of layers in the nucleation host. The invention proposes a recording media that overcomes the writeability problem of perpendicular recording media.

A magnetic property measuring system includes coil structures configured to apply a magnetic field to a sample, a light source configured to irradiate incident light to the sample, and a detector configured to detect polarization of light reflected from the sample. The magnetic field is perpendicular to a surface of the sample. Each coil structure includes a pole piece and a coil surrounding an outer circumferential surface of the pole piece. A wavelength of the incident light is equal to or less than about 580 nm.

A method for measuring magnetic characteristics is the method including applying a first magnetic field to a continuously moving magnetic recording medium to magnetically saturate the magnetic recording medium, applying a first polarized light to a surface of the magnetic recording medium to which the first magnetic field is being applied, and measuring a light polarization state of a first reflected light that is reflected, applying a second magnetic field having an opposite direction of the first magnetic field to the continuously moving magnetic recording medium to magnetically saturate the magnetic recording medium, applying a second polarized light to the surface of the magnetic recording medium to which the second magnetic field is being applied, and measuring a light polarization state of a second reflected light that is reflected, applying a third magnetic field having an opposite direction of the second magnetic field to the continuously moving magnetic recording medium, applying a third polarized light to the surface of the magnetic recording medium to which the third magnetic field is being applied, and measuring a light polarization state of a third reflected light that is reflected, and adjusting a strength of the third magnetic field so that a measurement value of the light polarization state of the third reflected light is a mean value of a measurement value of the light polarization state of the first reflected light and a measurement value of the light polarization state of the second reflected light, and obtaining the strength of the third magnetic field when the measurement value of the light polarization state of the third reflected light becomes equal to the mean value.

According to one embodiment of the present invention, a computer-implemented method for dynamically altering a frequency at which data scrubbing is performed on a memory device is disclosed. The computer-implemented method includes monitoring at least one of a temperature and a magnetic field of the memory device. The computer-implemented method further includes, responsive to determining that at least one of the temperature and the magnetic field of the memory device reaches and/or exceeds a predetermined threshold, respectively, increasing the frequency at which data scrubbing is performed on the memory device.

In a method of testing a multilayer structure containing a magnetic layer, one or more network parameters are measured of a waveguide that is electromagnetically coupled with the multilayer structure as a function of frequency and as a function of a magnetic field applied to the multilayer structure during the measuring of the network parameters. Based on the measured one or more network parameters, at least one magnetic property of the magnetic layer of the multilayer structure is determined. The network parameters in some embodiments are S-parameters. The at least one magnetic property may include an effective anisotropy field of the magnetic layer and/or a damping constant of the magnetic layer.

A multilayer exchange spring recording media consists of a magnetically hard magnetic storage layer strongly exchange coupled to a softer nucleation host. The strong exchange coupling can be through a coupling layer or direct. The hard magnetic storage layer has a strong perpendicular anisotropy. The nucleation host consists of one or more ferromagnetic coupled layers. For a multilayer nucleation host the anisotropy increases from layer to layer. The anisotropy in the softest layer of the nucleation host can be two times smaller than that of the hard magnetic storage layer. The lateral exchange between the grains is small. The nucleation host decreases the coercive field significantly while keeping the energy barrier of the hard layer almost unchanged. The coercive field of the total structure depends on one over number of layers in the nucleation host. The invention proposes a recording media that overcomes the writeability problem of perpendicular recording media.

A multilayer exchange spring recording media consist of a magnetically hard magnetic storage layer strongly exchange coupled to a softer nucleation host. The strong exchange coupling can be through a coupling layer or direct. The hard magnetic storage layer has a strong perpendicular anisotropy. The nucleation host consists of one or more ferromagnetic coupled layers. For a multilayer nucleation host the anisotropy increases from layer to layer. The anisotropy in the softest layer of the nucleation host can be two times smaller than that of the hard magnetic storage layer. The lateral exchange between the grains is small. The nucleation host decreases the coercive field significantly while keeping the energy barrier of the hard layer almost unchanged. The coercive field of the total structure depends on one over number of layers in the nucleation host. The invention proposes a recording media that overcomes the writeability problem of perpendicular recording media.