A recording layer for an optical data recording medium according to one embodiment of the present invention makes it possible to record an information signal by irradiation with laser beam. The recording layer for an optical data recording medium comprises metal oxides including a Mn oxide, a W oxide, and a Sn oxide. The atomic ratio of Mn with respect to the total number of atoms of metal elements constituting the metal oxides is 3-40 atm %.

Long term optical memory includes a storage medium composed from an array of silicon nanoridges positioned onto the fused silica glass. The array has first and second polarization contrast corresponding to different phase of silicon. The first polarization contrast results from amorphous phase of silicon and the second polarization contrast results from crystalline phase of silicon. The first and second polarization states are spatially distributed over plurality of localized data areas of the storage medium.

Long term optical memory includes a storage medium composed from an array of silicon nanoridges positioned onto the fused silica glass. The array has first and second polarization contrast corresponding to different phase of silicon. The first polarization contrast results from amorphous phase of silicon and the second polarization contrast results from crystalline phase of silicon. The first and second polarization states are spatially distributed over plurality of localized data areas of the storage medium.

A sintered compact target containing an element(s) (A) and an element(s) (B) as defined below is provided. The sintered compact target is free from pores having an average diameter of 1 μm or more, and the number of micropores having an average diameter of less than 1 μm existing in 40000 μm.sup.2 of the target surface is 100 micropores or less. The element(s) (A) is one or more chalcogenide elements selected from S, Se, and Te, and the element(s) (B) is one or more Vb group elements selected from Bi, Sb, As, P, and N. The provided technology is able to eliminate the source of grain dropping or generation of nodules in the target during sputtering, and additionally inhibit the generation of particles.

Long term optical memory includes a storage medium composed from an array of silicon nanoridges positioned onto the fused silica glass. The array has first and second polarization contrast corresponding to different phase of silicon. The first polarization contrast results from amorphous phase of silicon and the second polarization contrast results from crystalline phase of silicon. The first and second polarization states are spatially distributed over plurality of localized data areas of the storage medium.

Provided is a Mn—Ta—W—Cu—O-based sputtering target including, in the component composition, Mn, Ta, W, Cu, and O. The sputtering target has a relative density of at least 90%, and includes a crystal phase of Mn.sub.4Ta.sub.2O.sub.9. Also provided is a production method for the sputtering target.

A recording layer for an optical data recording medium according to one embodiment of the present invention makes it possible to record an information signal by irradiation with laser beam. The recording layer for an optical data recording medium comprises metal oxides including a Mn oxide, a W oxide, and a Sn oxide. The atomic ratio of Mn with respect to the total number of atoms of metal elements constituting the metal oxides is 3-40 atm %.

Long term optical memory includes a storage medium composed from an array of silicon nanoridges positioned onto the fused silica glass. The array has first and second polarization contrast corresponding to different phase of silicon. The first polarization contrast results from amorphous phase of silicon and the second polarization contrast results from crystalline phase of silicon. The first and second polarization states are spatially distributed over plurality of localized data areas of the storage medium.

Long term optical memory includes a storage medium composed from an array of silicon nanoridges positioned onto the fused silica glass. The array has first and second polarization contrast corresponding to different phase of silicon. The first polarization contrast results from amorphous phase of silicon and the second polarization contrast results from crystalline phase of silicon. The first and second polarization states are spatially distributed over plurality of localized data areas of the storage medium.

Long term optical memory includes a storage medium composed from an array of silicon nanoridges positioned onto the fused silica glass. The array has first and second polarization contrast corresponding to different phase of silicon. The first polarization contrast results from amorphous phase of silicon and the second polarization contrast results from crystalline phase of silicon. The first and second polarization states are spatially distributed over plurality of localized data areas of the storage medium.