A magnetic recording write head and system has a spin-torque oscillator (STO) located between the write head's write pole and trailing shield. The STO's ferromagnetic free layer is located near the write pole with a multilayer seed layer between the write pole and the free layer. The STO's nonmagnetic spacer layer is between the free layer and the STO's ferromagnetic polarizer. The polarizer may be the trailing shield of the write head, one or more separate polarizer layers, or combinations thereof. The STO electrical circuitry causes electron flow from the write pole to the trailing shield. The multilayer seed layer removes the spin polarization of electrons from the write pole, which enables electrons reflected from the polarizer layer to become spin polarized, which creates the spin transfer torque on the magnetization of the free layer. The multilayer seed layer includes a Mn or a Mn-alloy layer.

A magnetic recording write head and system has a spin-torque oscillator (STO) located between the write head's write pole and trailing shield. The STO's ferromagnetic free layer is located near the write pole with a multilayer seed layer between the write pole and the free layer. The STO's nonmagnetic spacer layer is between the free layer and the STO's ferromagnetic polarizer. The polarizer may be the trailing shield of the write head, one or more separate polarizer layers, or combinations thereof. The STO electrical circuitry causes electron flow from the write pole to the trailing shield. The multilayer seed layer removes the spin polarization of electrons from the write pole, which enables electrons reflected from the polarizer layer to become spin polarized, which creates the spin transfer torque on the magnetization of the free layer. The multilayer seed layer includes a Mn or a Mn-alloy layer.

A magnetic recording medium includes a substrate, an underlayer, and a magnetic layer that are arranged in this order. The magnetic layer has a granular structure including magnetic grains having a L1.sub.0 crystal structure, and grain boundary parts having a volume fraction in a range of 25 volume % to 50 volume %. The magnetic grains have a c-axis orientation with respect to the substrate. The grain boundary parts include a material having a lattice constant in a range of 0.30 nm to 0.36 nm, or in a range of 0.60 nm to 0.72 nm.

A Spin Hall Effect (SHE) assisted magnetic recording device is disclosed wherein a SHE layer and a conductor layer (CL) are formed between a main pole (MP) trailing side and a trailing shield (TS). When the SHE layer is a negative Spin Hall Angle (SHA) material, current (I.sub.a) flows from the SHE layer across the CL to a lead back to a source, or across the CL to one of the MP and TS. For a SHE layer with a positive SHA material, Ia flows from one of the MP or TS or from a lead across the CL to the SHE layer. Spin polarized current in the SHE layer applies spin transfer torque that tilts a local MP magnetization to a direction that enhances a MP write field, or that tilts a local TS magnetization to a direction that increases the TS return field and improves bit error rate.

A magnetic recording write head and system has a spin-torque oscillator (STO) located between the write head's write pole and trailing shield. The STO's ferromagnetic free layer is located near the write pole with a multilayer seed layer between the write pole and the free layer. The STO's nonmagnetic spacer layer is between the free layer and the STO's ferromagnetic polarizer. The polarizer may be the trailing shield of the write head, one or more separate polarizer layers, or combinations thereof. The STO electrical circuitry causes electron flow from the write pole to the trailing shield. The multilayer seed layer removes the spin polarization of electrons from the write pole, which enables electrons reflected from the polarizer layer to become spin polarized, which creates the spin transfer torque on the magnetization of the free layer. The multilayer seed layer includes a Mn or a Mn-alloy layer.

A Spin Hall Effect (SHE) assisted magnetic recording device is disclosed wherein a SHE layer and a conductor layer (CL) are formed between a main pole (MP) trailing side and a trailing shield (TS). When the SHE layer is a negative Spin Hall Angle (SHA) material, current (I.sub.a) flows from the SHE layer across the CL to a lead back to a source, or across the CL to one of the MP and TS. For a SHE layer with a positive SHA material, Ia flows from one of the MP or TS or from a lead across the CL to the SHE layer. Spin polarized current in the SHE layer applies spin transfer torque that tilts a local MP magnetization to a direction that enhances a MP write field, or that tilts a local TS magnetization to a direction that increases the TS return field and improves bit error rate.

A magnetic recording medium includes a substrate, an underlayer, and a magnetic layer that are arranged in this order. The magnetic layer has a granular structure including magnetic grains having a L1.sub.0 crystal structure, and grain boundary parts having a volume fraction in a range of 25 volume % to 50 volume %. The magnetic grains have a c-axis orientation with respect to the substrate. The grain boundary parts include a material having a lattice constant in a range of 0.30 nm to 0.36 nm, or in a range of 0.60 nm to 0.72 nm.

An electronic device and related operations are disclosed, including a communication circuit, a memory and a magnetic stripe transmission (MST) module for radiating a magnetic pulse. A processor implements the operations, including: controlling the MST module to change an emitted radiation pattern of the magnetic pulse in prespecified order to iteratively emit the plurality of radiation patterns, in response to detecting a prespecified event, selecting a presently emitted radiation pattern of the magnetic pulse, and storing information corresponding to the selected radiation pattern in the memory, or transmitting the information corresponding to the selected radiation pattern to the server.

A Spin Hall Effect (SHE) assisted magnetic recording device is disclosed wherein a stack of two SHE layers (SHE1 and SHE2) with an intermediate conductor layer is formed between a main pole (MP) trailing side and trailing shield (TS) bottom surface. SHE1 is a negative Spin Hall Angle (SHA) material while SHE2 is a positive SHA material. Current (I.sub.a) flows from SHE1 across the conductor layer to SHE2. In one embodiment, spin polarized current in SHE1 applies spin transfer torque that tilts a local MP magnetization to a direction that enhances a MP write field, and spin polarized current in SHE2 generates spin transfer torque that tilts a local TS magnetization to a direction that increases the TS return field and improves bit error rate. In alternative embodiments, one of SHE1 and SHE2 is omitted so that only one of the MP write field and TS return field is enhanced.

According to one embodiment, a magnetic disk device applies a bias voltage for measurement to a high frequency assist element according to a setting instruction of the bias voltage to measure a conduction current by in a recording head, calculates the resistance value in the supply path of the bias voltage from a relationship between the measured current and the bias voltage for measurement, and changes the bias voltage applied at the time of data recording based on the calculated resistance value.