An ionic liquid comprising: a cation (or conjugate acid), wherein the cation (or conjugate acid) is represented by General Formula (A) below or General Formula (B) below or General Formula (C) or General Formula (D) below or General Formula (E) below:

##STR00001## wherein R.sub.1 represents CH.sub.2CH.sub.2(CF.sub.2).sub.nCF.sub.3, where n is an integer ranging from 0 to 7, or an alkyl chain CH.sub.3, or CH.sub.2OH, or CH.sub.2CH.sub.2OH; R.sub.2 represents CH.sub.2CH.sub.2(CF.sub.2).sub.nCF.sub.3, where n is an integer ranging from 0 to 7, or a hydrogen atom H, or CH.sub.2OH, or CH.sub.2CH.sub.2OH; and R.sub.3 represents CH.sub.2CH.sub.2(CF.sub.2).sub.nCF.sub.3, where n is an integer ranging from 0 to 7.

Disclosed is a perpendicularly magnetized film structure using a highly heat resistant underlayer film on which a cubic or tetragonal perpendicularly magnetized film can grow, comprising a substrate of a cubic single crystal substrate having a (001) plane or a substrate having a cubic oriented film that grows to have the (001) plane; an underlayer formed on the substrate from a thin film of a metal having an hcp structure in which the [0001] direction of the thin metal film forms an angle in the range of 42 to 54 with respect to the <001> direction or the (001) orientation of the substrate; and a perpendicularly magnetized layer located on the metal underlayer and formed from a cubic material selected from a Co-based Heusler alloy and a cobalt-iron (CoFe) alloy having a bcc structure a constituent material, and grown to have the (001) plane.

A device includes a housing unit and a number of magnets. The housing unit includes a number of holes therein. The magnets are positioned in the holes. The magnets have a same pole orientation. It is appreciated that the magnets are positioned in the holes to form a mechanically balanced and magnetically unbalanced structure.

A substrate for a magnetic disk includes a substrate main body having two main surfaces, and a film that is provided on the main surfaces and is made of a material having a loss factor of 0.1 or more. The substrate for a magnetic disk including the film has a thickness T of 0.700 mm or less, and a thickness D [mm] of the film provided on the main surfaces and the thickness T [mm] of the substrate for a magnetic disk including the film satisfy a relationship D0.0082/T0.0015.

A magnetic-disk glass substrate has a circular center hole a pair of main surfaces and an edge surface. The edge surface has a side wall surface and chamfered surfaces interposed between the side wall surface and the main surfaces, and a roundness of an edge surface on an outer circumferential side is 1.5 m or less. Also, a midpoint A between centers of two least square circle respectively derived from outlines in a circumferential direction respectively obtained at two positions spaced apart by 200 m in a substrate thickness direction on the side wall surface on the outer circumferential side, and centers B and C respectively derived from a respective one of two chamfered surfaces on the outer circumferential side in the substrate thickness direction, are located such that a sum of respective distances between A and B, and A and C, is 1 m or less.

A magnetic-disk glass substrate according to the present invention is a doughnut-shaped magnetic-disk glass substrate having a circular hole provided in the center, a pair of main surfaces, and an outer circumferential end surface and an inner circumferential end surface each including a side wall surface and a chamfered surface that is formed between each main surface and the side wall surface. A measurement point is provided on the outer circumferential end surface every 30 degrees in the circumferential direction with reference to a center of the glass substrate, and when a curvature radius of a shape of a portion between the side wall surface and the chamfered surface is determined at each measurement point, the difference in the curvature radius between neighboring measurement points is 0.01 mm or less.

Disclosed is a perpendicularly magnetized film structure using a highly heat resistant underlayer film on which a cubic or tetragonal perpendicularly magnetized film can grow, comprising a substrate of a cubic single crystal substrate having a (001) plane or a substrate having a cubic oriented film that grows to have the (001) plane; an underlayer formed on the substrate from a thin film of a metal having an hcp structure in which the [0001] direction of the thin metal film forms an angle in the range of 42? to 54? with respect to the <001> direction or the (001) orientation of the substrate; and a perpendicularly magnetized layer located on the metal underlayer and formed from a cubic material selected from a Co-based Heusler alloy and a cobalt-iron (CoFe) alloy having a bcc structure a constituent material, and grown to have the (001) plane.

A device includes a housing unit and a number of magnets. The housing unit includes a number of holes therein. The magnets are positioned in the holes. The magnets have a same pole orientation. It is appreciated that the magnets are positioned in the holes to form a mechanically balanced and magnetically unbalanced structure.

Disclosed is a perpendicularly magnetized film structure that uses a highly heat resistant underlayer film on which a cubic or tetragonal perpendicularly magnetized film can grow with high quality, the structure comprising any one substrate (5) of a cubic single crystal substrate having a (001) plane, or a substrate having a cubic oriented film that grows to have the (001) plane; an underlayer (6) formed on the substrate (5) from a thin film of a metal having an hcp structure, such as Ru or Re, in which the [0001] direction of the thin metal film forms an angle in the range of 42? to 54? with respect to the <001> direction or the (001) orientation of the substrate (5); and a perpendicularly magnetized layer (7) located on the metal underlayer (6) and formed from a cubic material selected from the group consisting of a Co-based Heusler alloy, a cobalt-iron (CoFe) alloy having a bcc structure, and the like, as a constituent material, and grown to have the (001) plane.

The present disclosure generally relates to a tape head and a tape head drive including a tape head. The tape head comprises at least one same gap verify (SGV) module comprising a plurality of write transducer and read transducer pairs. Each write transducer is coupled to writer bonding pads via writer leads, and each read transducer is coupled to reading bonding pads via reader leads. An isolation shield is disposed between the write transducer and read transducer such that the isolation shield is disposed between each writer lead and each reader lead. The isolation shield acts as a Faraday cage to reduce cross-talk between the write and read transducers. The SGV module is configured to write data to a tape using the write transducers and read verify the data written on the tape using the read transducers such that the write transducers and read transducers are concurrently operable.