Odawara, Japan
Odawara, Japan

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Miura K.,Iwate University | Katada H.,HGST Japan | Oguma M.,Tohoku University | Nishida Y.,HGST Japan | Muraoka H.,Tohoku University
IEEE Transactions on Magnetics | Year: 2013

In this paper, the erase band generation mechanism is discussed focusing on both the magnetic field from background tracks and variation in medium microstructure as origins of erase bands. The edge positions of bits in an overwrite track was examined. According to the same principle as the easy/hard transition shift, magnetostatic interference from the background track is also likely to shift the edge position of overwrite track in the cross-track direction and these shifts result in a clear broadening of the erase band. Erase band widths measured for various linear densities of background and overwrite tracks verified the proposed mechanism qualitatively and the largest noise, corresponding to AC erased noise, emanated from easy edges according to numerical calculations. © 2013 IEEE.

Xu J.,HGST Japan | Shimizu Y.,Tohoku University | Furukawa M.,HGST Japan | Li J.,HGST Japan | And 6 more authors.
IEEE Transactions on Magnetics | Year: 2014

The fundamental performance of contact/clearance sensor, namely embedded contact sensor (ECS), is addressed in this paper. Both simulation and experiment results revealed that ECS is a promising sensor for low clearance and high reliability at subnanometer regime. The ECS dc signal intrinsically comes from multiple sources including TFC heater, air-bearing surface cooling, and friction heating at head/disk contact. Both ECS dc and ac signals detect head/disk contact. The dc signal comes from the sensor resistance change due to friction heating at contact, but the ac signal is dominated by spacing modulation caused by air-bearing vibration, and partially from the pulse-like friction heating. ECS ac signal responds significantly to disk microwaviness at narrow clearance region. Furthermore, ECS could detect asperities, pit, and lube mogul. The mechanism for asperity detection is friction heating. The mechanism for pit detection is worse cooling when sensor flying over the pit. That for mogul detection is better cooling at narrower spacing when the sensor is flying over the mogul. © 2014 IEEE.

Xu J.,HGST Japan | Shimizu Y.,Tohoku University | Liu J.,Hitachi Ltd. | Shiramatsu T.,HGST Japan | And 3 more authors.
2012 Digest APMRC - Asia-Pacific Magnetic Recording Conference: A Strong Tradition. An Exciting New Look! | Year: 2012

Pit detection study of a thermal contact sensor was carried out by both experiments and simulation. The experimental results showed that the thermal contact sensor was able to detect a small pit with good sensitivity. And the simulation study revealed that the mechanism of pit detection is due to worse cooling, which results in higher sensor temperature, because the sensor/disk spacing is larger on the pit. The maximum temperature increase is significant initially with increasing pit depth but saturates when the depth is larger than 60 nm. © 2012 DSI.

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