High-frequency inductance measurements and performance projections made for cusp-field single-pole heads

Abstract

High-frequency measurements of the inductance of cusp-field single-pole heads for perpendicular recording are made out to 13.5 GHz to determine their performance. The inductance of the pole heads examined are typically 1.2-1.9 nH with a self resonance at about 7-10 GHz. Inductance versus current measurements allow construction of the nonlinear eddy-current damped, thin-film head model. Comparison is made to a longitudinal recording head of similar size and turns. The effect of the medium underlayer as part of the head return path is shown to have minimal effect on the head inductance. Contact Tri-Pad heads are used to demonstrate the changes produced by the underlayer and to demonstrate apex and yoke saturation. The contact behavior is similar to that for a longitudinal thin-film head. The frequency dependence of the pole material permeability is discussed. The conclusions provide a practical bit rate limit for the cusp-field head based on head and write channel modeling, experimental high-frequency inductance data, and spin reversal considerations.Index Terms-High-frequency performance, nonlinear eddycurrent damped head model, single-pole cusp-field head.

Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head

“…The gradient can further be exploited to set up spin registers in quantum simulators 38 . The combination of large field and rapid switching 5 6 , which is difficult to achieve in typical research devices, will allow the implementation of very fast spin manipulation through magnetic resonance techniques 39 . At a pulse amplitude of 1 T, the nominal spin flip duration is 0.5 × γB 0 /2 π ≅18 ps for electrons and ∼12 ns for protons, which would be faster than any previously demonstrated values 40 41 42 .…”

“…At a pulse amplitude of 1 T, the nominal spin flip duration is 0.5 × γB 0 /2 π ≅18 ps for electrons and ∼12 ns for protons, which would be faster than any previously demonstrated values 40 41 42 . These flip rates will eventually be limited by the response time of the WH and pole material 5 6 .…”

“…This is far beyond the capability of static magnetic tips (∼5 × 10 6 T m −1 (refs 2 , 3 )) and that of nanoscale coils or microstrips (∼10 5 T m −1 (refs 3 , 4 )), and likely close to the highest experimentally achievable gradient for this kind of field source. In addition, write poles are rapidly switchable, potentially allowing for dynamical control of magnetic fields up to 1 GHz (refs 5 , 6 ) at low power consumption. With these features, the hard drive industry has created a tool that could enable important advances in many areas of nanoscale experimental physics.…”

Response of Magnetic Force Microscopy Probes under AC Magnetic Field

“…A perpendicular magnetic write head was employed as the AC magnetic field generator since it can produce AC magnetic field with very high frequency greater than 1 GHz [12,13]. In this study, the magnetic write head was biased with AC current of 30 mA to ensure that the main pole was magnetically saturated.…”

Magnetic field measurement for analysis of GHz response in SPT head using electron beam tomography

“…Eddy currents and magnetization dynamics in the yoke may be limiting factors at over 1 GHz [3,4]. Timeresolved Kerr microscopy had been used to evaluate high-frequency head response [5][6][7], but the dimensions of the magnetic pole in present write heads are less than the optical diffraction limit.…”