Hitachi, Ltd.

Hitachi Global Storage Technologies Netherlands B.v.

Hitachi Global Storage Technologies Japan, Ltd.

Fumiko Akagi

Masukazu Igarashi

Futoshi Tomiyama

Takuya Matsumoto

Yasutaka Nishida

Hideki Saga

Takehiko Hamaguchi

Kazuetsu Yoshida

Akira Ishikawa

Kimio Nakamura

Miki Hara

Hiroshi Ikeda

Tatsuya Hinoue

Tomoo Yamamoto

Atsushi Nakamura

Hiroaki Nemoto

Hideki Zaitsu

Takayuki Ichihara

Mitsuhiro Hashimoto

Embodiments of the present invention help to suppress the effects of thermal fluctuation in a thermally assisted magnetic field recording, and improve recording density. According to one embodiment, a recording area of a magnetic disk is heated and the full width at half maximum of an optical power distribution of a near field light generator is controlled to be 100 nm or less. Thereby, the cooling time of the magnetic disk is made 2 nm or less and the effects of thermal fluctuation are suppressed. Moreover, although an incomplete area of the magnetization reversal at the rear end of the magnetic domain is created with rapid cooling, by creating an overshoot at the rising end of the magnetic field waveform of the magnetic recording head, the incomplete area of the magnetization reversal can be overwritten, which is created at the rear end of the magnetic domain previously recorded by the overshoot magnetic field. Therefore, the expansion of the magnetic transition width can be suppressed, resulting in the recording density being improved.

Thermally assisted magnetic recording head, recording system, and recording method

One purpose of the invention according to one embodiment is to provide a magnetic recording apparatus of high recording density in which magnetization transition curvature amount of a recording pattern is small. In one embodiment, the center of a heating area is arranged at a track edge side of a recording pattern as compared with the width-direction center position of a main magnetic pole of a recording head, and a recording magnetic field is applied while a medium is locally heated at the time of signal recording. A switching magnetic field of the medium is locally reduced by heating, so that a line where the switching magnetic field of the medium is equal to the recording magnetic field from the head approaches the heating center position, and a desired recording pattern in which the transition curvature amount is reduced can be realized. Other systems and methods are also presented.

Near-field recording device having heating mechanism positioned near a trailing side of a magnetic pole

The aim of the present invention is to apply an intense magnetic field to a portion where an optical near-field is generated by a thermal assisted magnetic recording head with a scatterer having conductivity as an optical near-field generating element. To this end, a scatterer for generating an optical near-field is formed in a bottom portion of a slider, and a magnetic field is applied thereto using a coil. In order to increase the intensity of the magnetic field, a magnetic pole made of a soft magnetic material is formed over the scatterer.

Head for thermal assisted magnetic recording device, and thermal assisted magnetic recording device

A thermally assisted magnetic recording medium includes a substrate and at least two, i.e., first and second magnetic recording layers. These layers are hard magnetic layers and contain magnetic grains and a non-magnetic substance magnetically segregating the magnetic grains at grain boundaries. The first magnetic recording layer has a magnetic anisotropy energy K, a grain volume v, and energy for maintaining its recording magnetization Kv; the second magnetic recording layer has a magnetic anisotropy energy K, a grain volume v, and energy for maintaining its recording magnetization Kv; and the ratio Kv/kT of Kvto a thermal fluctuation energy kT, where krepresents a Boltzmann constant and T represents an absolute temperature, and the ratio Kv/kT of Kvto kT satisfy the following conditions: Kv/kT is larger than Kv/kT at room temperature, but is smaller than Kv/kT at temperatures around the Curie temperature of the first magnetic recording layer.

Thermally assisted recording media and system

A thermally assisted magnetic recording system is provided to achieve excellent thermal resistance and low noise. In one embodiment, a magnetic recording medium is used, in which the magnetic intergrain exchange coupling is large to let the magnetization be thermally stable by coupling the magnetic grains constituting the recording layer at room temperature (the temperature maintaining the magnetization) and reduced by heating during recording to let the recording magnetization transition slope become steep. Parameter A normalizing the slope around the coercivity of the MH-loop of the medium is 1.5&#x2266;A&#x3c;6.0 at room temperature, and it becomes approximately 1.0 with heating.

Thermally assisted recording system

The optimum head-field intensity for saturation recording is assumed to be 560&#xd7;10A/m or more. Under a condition where the recording track width of an information recording medium is equal to or less than 60 nm, the optimum head-field intensity Y satisfies the following inequalities (1) and (2):&#x2267;(&#x2212;119&#xd7;+4135)&#xd7;1000&#x2003;&#x2003;(1)&#x2266;(&#x2212;119&#xd7;+const)&#xd7;1000&#x2003;&#x2003;(2)where X denotes the nondimensional value of the recording track width divided by 10m, and Y denotes a magnetic field (expressed in units of A/m) which a magnetic pole for head-field application applies to the center of the information recording medium in the direction of the thickness thereof. Note that const=&#x2212;0.8&#xd7;v+33.7&#xd7;v+4250 if the relative velocity v between the head and the medium at the position of the head is less than 20 m/sec, or const=4600 if the velocity v is equal to or more than 20 m/sec.

Thermally assisted magnetic recording system

An AFC magnetic recording medium having a three-layered ferromagnetic structure capable of reducing noises without deteriorating thermal stability is provided in order to achieve ultra-high recording density. In one embodiment, the AFC magnetic recording medium has a magnetic recording layer formed on a substrate via an underlayer, the magnetic recording medium consisting of a first ferromagnetic layer formed on the underlayer, a second ferromagnetic layer formed on the first ferromagnetic layer via a nonmagnetic layer inducing the antiferromagnetic interaction, and a third ferromagnetic layer formed on the second ferromagnetic layer, wherein the center of gravity G of the magnetic recording medium is defined using the distance tfrom the upper surface of the third ferromagnetic layer as:

Magnetic recording media with ultra-high recording density

There are provided a magnetic head and a magnetic disk apparatus wherein an upper magnetic pole is so shaped that, at a position where skew angle is maximum, the maximum of its projected length in the radial direction of a magnetic disk is not more than the track pitch of the magnetic disk, whereby acceleration of thermal relaxation of information recorded on adjacent tracks is obviated even in an area where the skew angle is large.

Magnetic head with high reliability of the data protection, magnetic disk apparatus including the magnetic head and the method of recording information on the magnetic disk apparatus without miserasing the previously recorded data

MAGNETIC HEAD WITH HIGH RELIABILITY OF THE DATA PROTECTION, MAGNETIC DISK APPARATUS INCLUDING THE MAGNETIC HEAD AND THE METHOD OF RECORDING INFORMATION ON THE MAGNETIC DISK APPARATUS WITHOUT MISERASING THE PREVIOUSLY RECORDED DATA

A magnetic recording system includes a magnetic recording medium including a magnetic layer, the magnetic layer being composed of magnetic grains, and a magnetic head including a recording unit and a reproducing unit. An orientation of an axis of easy magnetization of the magnetic grains is three-dimensionally distributed. An average angle between a direction of an axis of easy magnetization of each of the magnetic grains and a surface of the magnetic recording medium is within a range of 20&deg; to 30&deg;. A squareness ratio Mr/Ms of a remanent magnetization Mr of the magnetic recording medium to a saturation magnetization Ms of the magnetic recording medium is equal to 0.5 or more and is equal to 0.6 or less. A recording density of information which is recorded onto the magnetic recording medium is equal to 360 kfci or more.

Magnetic recording system including magnetic recording medium having three-dimensional random orientation of axis of easy magnetization

An object is to provide a magnetic recording medium giving high resolution, low noise and little thermal fluctuation and thus suitable for high density magnetic recording, and a high-capacity magnetic recording device realized by using this medium. A thin film type magnetic recording medium is used, having at least 2 magnetic layers formed on a non-magnetic substrate and a non-magnetic intermediate layer that is interposed between the magnetic layers and causes the magnetizations of the magnetic layers to be anti-parallel to one another, and wherein the ratio HkB/HkA of the anisotropic magnetic field strength HkB of the magnetic layer on the side near to the substrate to the anisotropic magnetic field strength HkA of the magnetic layer on the side far from the substrate is 0.7 or less, more preferably at least 0.4 and not more than 0.65.

Magnetic recording medium

A magnetic recording system which can suppress an influence by a thermal fluctuation and is suitable for the high density magnetic recording in which excellent S/N ratio and resolution are obtained is provided. There is provided a magnetic recording system constructed by: a magnetic recording medium having a magnetic layer formed on a substrate through an underlayer; a driving unit for driving the medium in the recording direction; a magnetic head constructed by a recording unit and a reproducing unit; an apparatus for relatively moving the magnetic head to the magnetic recording medium; and a recording reproduction signal processing apparatus for performing a signal input to the magnetic head and an output signal reproduction from the magnetic head, wherein the reproducing unit of the magnetic head is constructed by a magneto-resistance effect type head and the system has a recording magnetization pattern in which a magnetization transition length of the magnetic recording medium is equal to 70 nm or less, the direction of an axis of easy magnetization of the magnetic particles in the magnetic layer of the magnetic recording medium is three-dimensionally oriented. Even after the elapse of 100 hours after the recording and at a linear recording density of 360 kfci, a reproduction output hardly decreases. A degree of deterioration of the S/N ratio of the output to the noises and the resolution are smaller than that of the conventional system.

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Tokyo, Japan

Fumiko Akagi