Heat assisted magnetic recording (HAMR) heads including components made of nickel alloys

A magnetic device that includes a write pole having a write pole tip; a read pole having a read pole tip; an optical near field transducer; and a contact pad. The contact pad includes Ni100-aXa, wherein X is chosen from Ru, Re, Zr, Cr, and Cu; and a is the atomic percent of the element X, and can range from about 20 to about 90. The optical near field transducer is positioned between the read pole and the write pole and the contact pad is positioned adjacent the write pole opposite the optical near field transducer.

BACKGROUND

Heat assisted magnetic recording (referred to herein as “HAMR”) technology is a promising approach for increasing storage density beyond 1 Tbit/inch2. HAMR utilizes a laser to heat the recording medium to reduce its coercivity below the magnetic field applied from the writer. Advances in the construction and materials used in HAMR heads can further advance the use thereof for data storage.

SUMMARY

Disclosed is a magnetic device that includes a write pole; a read pole; an optical near field transducer; and a contact pad. The contact pad includes Ni100-aXa, wherein X is chosen from Ru, Re, Zr, Cr, and Cu; and a is the atomic percent of the element X, and can range from about 20 to about 90. The optical near field transducer is positioned between the read pole and the write pole and the contact pad is positioned adjacent the write pole opposite the optical near field transducer.

Also disclosed is a slider that includes a slider body having a leading edge, a trailing edge and an air bearing surface; a write pole on the slider body and having a pole tip adjacent the air bearing surface; a read pole on the slider body and having a pole tip adjacent the air bearing surface; an optical near field transducer on the slider body adjacent the air bearing surface; and a contact pad on the slider body adjacent the air bearing surface. The contact pad includes Ni100-aXa, wherein X is chosen from Ru, Re, Zr, Cr, and Cu; and a is the atomic percent of the element X, and can range from about 20 to about 90. The optical near field transducer is positioned between the read pole and the write pole and the contact pad is positioned adjacent the write pole opposite the optical near field transducer.

Further disclosed is a disc drive that includes a suspension and a slider attached to the suspension. The slider includes a slider body having a leading edge, a trailing edge and an air bearing surface; a write pole on the slider body and having a pole tip adjacent the air bearing surface; a read pole on the slider body and having a pole tip adjacent the air bearing surface; an optical near field transducer on the slider body adjacent the air bearing surface; and a contact pad on the slider body adjacent the air bearing surface. The contact pad includes Ni100-aXa, wherein X is chosen from Ru, Re, Zr, Cr, and Cu; and a is the atomic percent of the element X, and can range from about 20 to about 90. The optical near field transducer is positioned between the read pole and the write pole and the contact pad is positioned adjacent the write pole opposite the optical near field transducer.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying set of drawings that form a part hereof and in which are shown by way of illustration several specific embodiments. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

“Include,” “including,” or like terms means encompassing but not limited to, that is, including and not exclusive. It should be noted that “top” and “bottom” (or other terms like “upper” and “lower”) are utilized strictly for relative descriptions and do not imply any overall orientation of the article in which the described element is located.

FIG. 1is a perspective view of disc drive10including an actuation system for positioning slider12over track14of magnetic medium16. The particular configuration of disc drive10is shown for ease of description and is not intended to limit the scope of the present disclosure in any way. Disc drive10includes voice coil motor18arranged to rotate actuator arm20on a spindle around axis22. Load beam24is connected to actuator arm20at head mounting block26. Suspension28is connected to an end of load beam24and slider12is attached to suspension28. Magnetic medium16rotates around an axis30, so that the windage is encountered by slider12to keep it aloft a small distance above the surface of magnetic medium16. Each track14of magnetic medium16is formatted with an array of data storage cells for storing data. Slider12carries a magnetic device or transducer (not shown inFIG. 1) for reading and/or writing data on tracks14of magnetic medium16. The magnetic transducer utilizes additional electromagnetic energy to heat the surface of medium16to facilitate recording by a process termed heat assisted magnetic recording (HAMR).

A HAMR transducer includes a magnetic writer for generating a magnetic field to write to a magnetic medium (e.g. magnetic medium16) and an optical device to heat a portion of the magnetic medium proximate to the write field.FIG. 2is a cross sectional view of a portion of HAMR magnetic device40and a portion of associated magnetic storage medium42. HAMR magnetic device40includes write pole44and return pole46coupled by pedestal48. Coil50comprising conductors52and54encircles the pedestal and is supported by an insulator56. As shown, magnetic storage medium42is a perpendicular magnetic medium comprising magnetically hard storage layer62and soft magnetic underlayer64but can be other forms of media, such as patterned media. A current in the coil induces a magnetic field in the pedestal and the poles. Magnetic flux58exits the recording head at air bearing surface (ABS)60and is used to change the magnetization of portions of magnetically hard layer62of storage medium42enclosed within region58. Near field transducer66is positioned adjacent the write pole44proximate air bearing surface60. Near field transducer66is coupled to waveguide68that receives an electromagnetic wave from an external source such as a laser. An electric field at the end of near field transducer66is used to heat a portion69of magnetically hard layer62to lower the coercivity so that the magnetic field from the write pole can affect the magnetization of the storage medium.

Portions of an exemplary magnetic device, for example a HAMR magnetic device are depicted inFIG. 3.FIG. 3is a view from the storage medium (storage medium42inFIG. 2) looking up at the ABS. The magnetic device100depicted inFIG. 3includes a read pole105, a write pole115, an optical near field transducer (also referred to as a NFT)110and a contact pad120. The relative sizes and shapes of the components depicted inFIG. 3is for illustration purposes only and should not be taken as limiting any of the components (including those depicted and those not depicted). As seen inFIG. 3, the optical near field transducer110is positioned between the write pole115and the read pole105. The contact pad120is positioned adjacent the write pole115opposite the optical near field transducer110. The contact pad120is closest to the trailing edge (designated as TE inFIG. 3), with the read pole105being closest to the leading edge (designated as LE inFIG. 3).

In embodiments, the contact pad has a width (in the direction from the trailing edge to the leading edge) from 1 micrometer (μm) to 4 μm, in embodiments from 1.25 μm to 1.75 μm, and in embodiments about 1.5 μm.

Disclosed magnetic devices can also include heat sinks that are formed of a nickel alloy.FIG. 4illustrates an exemplary embodiment of a magnetic device101. The exemplary magnetic device101includes the components discussed above (numbered similarly) and also includes an optional heat sink125. The heat sink125can be positioned around at least a portion of the write pole115. Generally, the heat sink125functions to dissipate heat from the write pole115. In embodiments at least two sides of a write pole are surrounded by a heat sink. In embodiments, such as that depicted inFIG. 4, at least three sides of a write pole115are surrounded by a heat sink125. In embodiments, all four sides of a write pole can be surrounded by a heat sink.

In disclosed magnetic devices, the contact pad120, the heat sink125, or both can be formed from an alloy that includes nickel (Ni). In embodiments, the nickel alloy can be described as NiX. The alloy can also be described as Ni100-aXawith a being the atomic percent of the element X. X can be chosen from ruthenium (Ru), rhenium (Re), zirconium (Zr), chromium (Cr), Copper (Cu) and combinations thereof. In embodiments, X is Ru, Cr, or combinations thereof. In embodiments, X is Ru or Cr. In embodiments, X is Ru. In embodiments, the element X can be an element that if the contact pad were made entirely of it, the contact pad would tend to protrude towards the ABS farther then if the contact pad were made entirely of nickel.

In embodiments, a can range from 20 atomic percent (at %) to 90 at %; from 40 at % to 80 at %; or from 60 at % to 80 at %. In embodiments, a can range from 20 at % to 70 at %, or from 30 at % to 60 at %; or from 40 at % to 50 at %. In embodiments where X is Ru, a can range from 20 at % to 90 at %; from 40 at % to 80 at %; or from 60 at % to 80 at %. In embodiments were X is Cr, a can range from 20 at % to 70 at %; from 30 at % to 60 at %; or from 40 at % to 50 at %.

Nickel alloys as utilized herein may also optionally include a third component. The optional third component can be one that is chosen to affect various properties of the alloys. For example, the optional third component can be chosen to increase the hardness of the alloy, increase the grain stability, increase the wear resistance, decrease the stress, increase the resistance to corrosion, or some combination thereof. In embodiments, the optional third alloy can be chosen from: ruthenium (Ru), rhenium (Re), copper (Cu), chromium (Cr), zirconium (Zr), tungsten (W), and iron (Fe) for example. In embodiments a nickel alloy with an optional third alloy can be described by the formula Ni(100-a-b)XaYb, where X is chosen from ruthenium (Ru), rhenium (Re), zirconium (Zr), chromium (Cr), and Copper (Cu); Y is chosen from ruthenium (Ru), rhenium (Re), copper (Cu), chromium (Cr), zirconium (Zr), tungsten (W), and iron (Fe); a can range from 20 at % to 90 at %; and b can range from 1 at % to 50 at %.

Disclosed magnetic devices that include a contact pad, heat sink, or both formed from Ni100-aXaalloys can have desirable levels of protrusion at elevated temperatures (such as those encountered in HAMR). In embodiments, contact pads, heat sinks, or both formed from Ni100-aXaalloys can have a level of protrusion that is similar to the protrusion of the write pole. In embodiments, contact pads, heat sinks, or both formed from Ni100-aXaalloys can have a level of protrusion that is slightly more protruded than the write pole. In embodiments, contact pads, heat sinks, or both formed from Ni100-aXaalloys can have a level of protrusion that is not more than 10% more than the protrusion of the write pole.

Alloys used herein for the contact pad, heat sink, or both may also have other properties. In embodiments, alloys used herein for the contact pad, heat sink, or both may be non-magnetic. Experimental results and results from models show that NiRu alloys (for example) become non-magnetic above 15 at % ruthenium (Ru). In embodiments, the alloys utilized for the contact pad, heat sink, or both can be relatively resistant to corrosion. In embodiments the alloys utilized for the contact pad, heat sink, or both can have a positive corrosion potential (Ecorr) relative to the write pole material. In embodiments, alloys used herein for the contact pad, heat sink, or both may have low stress, high wear resistance, acceptable adhesion with other materials in the magnetic device, are capable of being planarized (for example by using chemical mechanical polishing (CMP)), have low roughness, have no more than a minimal mismatch of the coefficient of thermal expansion (CTE) with that of the write pole material (for example CoFe), have a relatively high thermal conductivity, have a thermally stable microstructure, can be deposited without voids (i.e., conformal deposition), or some combination thereof these properties (and/or others not described herein).

Nickel alloys utilized herein can be deposited via sputtering methods, electrodeposition methods, or other methods.

Magnetic devices disclosed herein can also include other structures. Magnetic devices disclosed herein can also be incorporated into larger devices. For example, sliders can include magnetic devices as disclosed herein. Exemplary sliders can include a slider body that has a leading edge, a trailing edge, and an air bearing surface. The write pole, read pole, optical near field transducer and contact pad (and optional heat sink) can then be located on (or in) the slider body. Such exemplary sliders can be attached to a suspension which can be incorporated into a disc drive for example.

EXAMPLES

While the present disclosure is not so limited, an appreciation of various aspects of the disclosure will be gained through a discussion of the examples provided below.

Recession/Protrusion of NiRu Alloys

In order to evaluate the recession and protrusion profile of various NiRuxalloys relative to an exemplary FeCo write pole, a multilayer stack of varying composition of NiRu (beginning with 100 at % Ni and ending with 100 at % Ru) intercalated between FeCo was deposited. Scanning electron microscope (SEM) images of the multilayer stack can be seen inFIGS. 5A and 5B.FIG. 5Ashows a 15000× magnification andFIG. 5Bshows a 60000× magnification.

FIG. 6shows the atomic force microscopy (AFM) analysis of the multilayer stack after both slider level aqueous kiss-lap (AKL) and a 70° 50 Å etch diamond like carbon (DLC) process. From looking at the graph inFIG. 6it can be seen that pure Ni recesses and pure Ru protrudes with respect to FeCo, while NiRu layers in the composition range of Ni40Ru60to Ni20Ru80is substantially co-planar or has minimal recession/protrusion relative to FeCo.

Thermal Stability of NiRu Alloys

Thermal stability of NiRu alloys was tested by measuring the evolution of stress versus temperature.FIG. 7Aand Table 1 below shows the as deposited stress (MPa) as a function of the atomic % of ruthenium.FIGS. 7B and 7Cshows the stress changes in Ni40Ru60(FIG.7B) and Ni20Ru80(FIG. 7C). As can be seen fromFIGS. 7B and 7C, both Ni40Ru60and Ni20Ru80undergo small stress changes (230 and 81 MPa respectively) up to 200° C., which demonstrates good thermal stability of the alloys.

FIGS. 8A and 8Bshow AFM scans of as-deposited (FIG. 8A) versus post-anneal at 300° C. for two hours (FIG. 8B). The post-anneal AFM images don't show grain growth or roughness increases corroborating the good thermal stability of the material up to 300° C.

Structural Stability of NiRu Alloys

The structural stability of the materials was measured by X-ray diffraction (XRD) in the as-deposited and post-anneal states.FIG. 9Ashows that the as-deposited pure Ni exhibits a single textured fcc (111) crystal state while pure Ru and NiRu alloys show multi-textured hcp phase only.FIG. 9Bshows that the NiRu alloys shows a 20 shift of 0.1°, which corresponds to a residual strain of negligible amount of 0.2%. No peak broadening of the post-anneal film demonstrates good structural stability. It should be noted that the single textured fcc (111) NiRu alloys are metastable and remain so even after a 300° C. anneal.

Chemical Stability of NiRu Alloys

The corrosion potentials (Ecorr) of nickel alloys were tested to assess the chemical robustness of the materials. The corrosion potentials were tested at 0.1 M NaCl pH 5.9 (neutral media) and at pH 3 (acidic media). The results are shown in Tables 2 and 3 below.

As seen from Tables 2 and 3, the nickel alloys exhibited high resistance to corrosion (as indicated by the positive Ecorr) and good passivity in both neutral (Table 2) and acidic (Table 3) environments. All of the nickel alloys tested had better corrosion resistance than FeCo (Ecorrvs. SCE=−0.30), Ni45Fe55(Ecorrvs. SCE=−0.25), and Cr (Ecorrvs. SCE=0.03).FIGS. 10A and 10Bshow the potential versus current density scans of pure nickel, pure ruthenium, and various NiRu alloys at 0.1 M NaCl pH 5.9 (FIG. 10A) and pH 3 (FIG. 10B) respectively.

Thus, embodiments of HEAT ASSISTED MAGNETIC RECORDING (HAMR) HEADS INCLUDING COMPONENTS MADE OF NICKEL ALLOYS are disclosed. The implementations described above and other implementations are within the scope of the following claims. One skilled in the art will appreciate that the present disclosure can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation.