A read head composed of a spin-torque oscillator (STO) has been proposed for a hard disk drive (HDD). The STO read head senses the media field as modulation in its oscillation frequency, enabling high signal-transfer rate beyond the limit of ferromagnetic relaxation. Although frequency stability of STOs is poor because of their frequency nonlinearity, the problem of poor stability is expected to be overcome by employing delay detection. In this study, we demonstrate delay detection of the STO signals frequency-modulated by nanosecond-pulsed magnetic fields. For pulses with duration time of 1, 3, and 5 ns, we show that the phase shifts Δφ of the STO signals induced by the pulsed magnetic field are approximately proportional to the pulse area. Furthermore, output signals of delay detection are calculated using the single-shot waveforms, which show distinct pulsed forms corresponding to the respective pulsed magnetic fields.
[1]
K. Mizushima,et al.
Signal-to-noise ratios in high-signal-transfer-rate read heads composed of spin-torque oscillators
,
2010
.
[2]
Rie Sato,et al.
Frequency transition of spin-torque oscillator under the magnetic-field pulse in nanosecond range
,
2011
.
[3]
K. Mizushima,et al.
Numerical Simulation on Temporal Response of Spin-Torque Oscillator to Magnetic Pulses
,
2010
.
[4]
B. Gurney,et al.
Nanoscale magnetic field detection using a spin torque oscillator
,
2010,
Nanotechnology.
[5]
Real-Time Measurement of Temporal Response of a Spin-Torque Oscillator to Magnetic Pulses
,
2013
.