Disclosed is a method of lubrication including a step of lubricating a machine with a lubricating composition, the lubricating composition including 20-100% ionic liquid or of a mixture of several ionic liquids. The ionic liquid or the mixture is selected from at least: an anion A.sup.− chosen from sulfonylimides, the substituent(s) of which is (are) independently chosen from a fluoroalkyl, fluoroether, perfluorinated alkyl or perfluoroether group; and a cation C.sup.+ including a nitrogen-containing heterocycle or a quaternary ammonium, the substituent(s) of which is (are) independently chosen from: a hydrogen atom or alkyl, alkoxy, fluorinated alkyl, perfluorinated alkyl, alkylsilane, alkyl alcohol, vinyl, alkyl allyl, ether or polyether groups having a linear or branched chain having 1-3 carbon atoms. The deposition start temperature in thin film of the ionic liquid or of the mixture of ionic liquids is at least equal to 330° C. The lubricating composition reduces deposits formed in the machine.

A multidentate lubricant comprising an anchoring moiety Ra attached to a plurality of sidechain moieties —(Rb—Re) according to the general formula: Ra—(Rb—Re).sub.x; wherein Ra is a multivalent radical of valance x; and each sidechain includes a perfluoroethyl ether moiety. The lubricant can be used in conjunction with a magnetic recording medium and/or a magnetic data storage system.

In one embodiment, a multidentate perfluoropolyether (PFPE) lubricant has the formula S.sub.e-S.sub.o-S.sub.i-S.sub.L-S.sub.i-S.sub.o-S.sub.e, where each S.sub.o includes at least one perfluoroethyl ether unit, S.sub.L is a linker segment, and each S.sub.e and S.sub.i include at least one functional group configured to attach to a surface. In another embodiment, a multi dentate PFPE lubricant has the formula S.sub.e-S.sub.o(a)-S.sub.i-S.sub.m-S.sub.i-S.sub.o(b)-S.sub.e, where each S.sub.o(a), S.sub.o(b), and S.sub.m include at least one perfluoroethyl ether unit with the proviso that S.sub.m has a different number of perfluoroethyl ether units than at least one of So.sub.(a) and S.sub.o(b), and each S.sub.e and S.sub.i include at least one functional group configured to attach to a surface.

A compound of the formula (1), and lubricant, and magnetic disk each using the same
A-OCH.sub.2RfCH.sub.2B(1)
wherein A is a group of the formula (a) below, B is a group of the formula (b) or (c) or (d) below, p is 0, 1 or 2, q is a real number of 2 to 10, R is C.sub.1-4 fluoroalkyl, Ar is unsubstituted or substituted aromatic group with C.sub.1-30 alkyl or C.sub.1-30 alkoxyl, Rf is CF.sub.2CF.sub.2O(CF.sub.2CF.sub.2CF.sub.2O).sub.xCF.sub.2CF.sub.2 or CF.sub.2CF.sub.2CF.sub.2O(CF.sub.2CF.sub.2CF.sub.2CF.sub.2O).sub.yCF.sub.2CF.sub.2CF.sub.2, x and y are each a real number of 0 to 50. ##STR00001##

A lubricant compound is contained in a lubrication layer of a magnetic disk in which at least a magnetic layer, a protective layer, and a lubrication layer are sequentially provided on a substrate, and the lubricant compound contains a component A represented by Chemical formula 1 and a component B represented by Chemical formula 2: ##STR00001##
wherein X in Chemical formula 1 represents OH ##STR00002##
wherein X in Chemical formula 2 represents OCH.sub.2CH(OH)CH.sub.2OH,
and the lubricant compound further contains a component C made of a specific compound having a phosphezene ring in the structure thereof.