A Numerical Investigation of the Nanoscale Heat Transfer in Heat Assisted Magnetic Recording

Author(s):  
Yueqiang Hu ◽  
Haoyu Wu ◽  
Yonggang Meng ◽  
David Bogy

The heat management problem in the heat assisted magnetic recording (HAMR) has been a long-term issue. In this paper, we investigated the temperature increase of a “lollipop” type near field transducer (NFT) in HAMR. We included the electromagnetic (EM) field analysis in the modeling and considered the back-heating from the media to the head with various heat transfer mechanisms. The results showed that the overcoat layer of the NFT plays an important role for protecting the NFT from high temperature. Degradation of the overcoat layer may result in the early failure of the NFT.

Author(s):  
Haoyu Wu ◽  
David Bogy

The near field transducer (NFT) overheating problem is an issue the hard disk drive (HDD) industry has faced since heat-assisted magnetic recording (HAMR) technology was first introduced. In this paper, a numerical study of the head disk interface (HDI) is performed to predict the significance of the nanoscale heat transfer due to the back heating from the disk. A steady-state heat transfer problem is first solved to get the disk temperature profile. Then an iterative simulation of the entire HDI system is performed. It shows that the heat transfer coefficient in the HDI increases to about 6:49 × 106 W/(m2K) when the clearance is 0:83 nm. It also shows that in the free space laser scenario, the simulation result is close to the experimental result.


Author(s):  
Shaomin Xiong ◽  
Robert Smith ◽  
Erhard Schreck

Abstract Heat assisted magnetic recording (HAMR) is a promising technology for the next generation hard disk drives (HDDs). Understanding the heat transfer at nanoscales and implementing a proper thermal management scheme become very critical as a few heat sources and energy delivery components are compactly integrated in a HAMR drive. Recently, a back-heating experimental setup is used to study heat transfer behavior. It is found that the detection of head disk contact and head disk spacing control become more complicated in this experimental setup because the local heating generates a protrusion on the media surface. In this paper, we demonstrate a method to enhance the contact detection sensitivity significantly by modulating the head disk spacing. It shows that a light contact between the head TFC protrusion and media protrusion can be effectively detected. Thereafter, the media protrusion can be measured and the head disk spacing can be well set.


Author(s):  
Shaomin Xiong ◽  
Robert Smith ◽  
Na Wang ◽  
Dongbo Li ◽  
Erhard Schreck ◽  
...  

Heat assisted magnetic recording (HAMR) promises to deliver higher storage areal density than the current perpendicular magnetic recording (PMR) product. A laser is introduced to the HAMR system to heat the high coercively magnetic media above the Curie temperature (Tc) which is as high as 750 K in order to enable magnetic writing. The thermal response of the media becomes very critical for the success of the data writing process. In this paper, a new method is proposed to understand the transient thermal behavior of the HAMR media. The temperature response of the media is measured based on thermal erasure of the magnetically written signal. A lumped model is built to simplify the heat conduction problem to understand the transient thermal response. Finite element modeling (FEM) is implemented to simulate the transient thermal response of the media due to the laser pulse heating. The experimental and simulation results show fairly good agreement.


Nanophotonics ◽  
2015 ◽  
Vol 4 (4) ◽  
pp. 503-510 ◽  
Author(s):  
Jacek Gosciniak ◽  
Marcus Mooney ◽  
Mark Gubbins ◽  
Brian Corbett

AbstractTwo main ingredients of plasmonics are surface plasmon polaritons (SPP) and localized surface plasmon resonances (LSPR) as they provide a high degree of concentration of electromagnetic fields in the vicinity of metal surfaces, which is well beyond that allowed by the diffraction limit of optics. Those properties have been used in the new technique of heat assisted magnetic recording (HAMR) to overcome an existing limit of conventional magnetic recording by utilizing a near-field transducer (NFT). The NFT designs are based on excitation of surface plasmons on a metal structure, which re-radiate with a subdiffraction limited light spot confined in the near field. In this paper, we propose a novel “droplet”-shaped NFT, which takes full advantage of a recenltly proposed Mach–Zehnder Interferometer (MZI), a coupling arrangement that allows optimal coupling of light to the transducer. The droplet design ensures better impedance match with the recording media and, consequently, better coupling of power. The droplet design results in very high enhancement of the electric field and allows the confinement of light in a spot size much smaller than the present stateof- the-art lollipop transducer.


2018 ◽  
Vol 57 (9S2) ◽  
pp. 09TB01
Author(s):  
Katsuji Nakagawa ◽  
Kousuke Kimura ◽  
Yoshihiko Hayashi ◽  
Kyosuke Tamura ◽  
Yoshito Ashizawa ◽  
...  

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