Thermo-magnetic recording method

Claim 2

A thermomagnetic recording method using a thermomagnetic recording medium including a laminated film consisting of a first (11) and a second magnetic thin film (12) having perpendicular magnetic anisotropy and a third magnetic thin (13) film having in-plane magnetic anisotropy or small perpendicular magnetic anisotropy interposed therebetween, laminated by being magnetically coupled to the adjoining films in turn, comprising the steps of: modulating in accordance with an information signal to be recorded a first heating condition to heat said medium to a temperature T₁ which is virtually above the Curie temperature T C1 of said first magnetic thin film and not causing reversal of the magnetic moment in said second magnetic thin film and a second heating condition to heat the same to a temperature T₂ which is above said temperature T C1 and sufficient to cause reversal of the magnetic moment in said second magnetic thin film; and cooling the medium from the heated states so that record magnetization is formed in said thermomagnetic recording medium.

Claim 3

A thermomagnetic recording method using a thermomagnetic recording medium including a laminated film consisting of a first and a second magnetic thin film having perpendicular magnetic anisotropy and a third magnetic thin film interposed therebetween, laminated by being magnetically coupled to the adjoining films in turn, said third magnetic thin film being made of a rare earth rich metallic film, which has in-plane magnetic anisotropy or smaller perpendicular magnetic anisotropy than that of said first and second magnetic thin films at room temperature and has a temperature characteristic of the effective anisotropy constant K being convex upward or linear, and having its saturation magnetization M S being from 0 to 450 emu/cm³ at room temperature, comprising the steps of: modulating in accordance with an information signal to be recorded a first heating condition to heat said medium to a temperature T₁ which is virtually above the Curie temperature T C1 of said first magnetic thin film and not causing reversal of the magnetic moment in said second magnetic thin film and a second heating condition to heat the same to a temperature T₂ which is above said temperature T C1 and sufficient to cause reversal of the magnetic moment in said second magnetic thin film; and cooling the medium from the heated states so that record magnetization is formed in said thermomagnetic recording medium.

Claim 4

A thermomagnetic recording method using a thermomagnetic recording medium including a laminated film consisting of a first and a second magnetic thin film having perpendicular magnetic anisotropy and a third magnetic thin film interposed therebetween, laminated by being magnetically coupled to the adjoining films in turn, said third magnetic thin film being made of a rare earth rich metallic film, which has in-plane magnetic anisotropy or smaller perpendicular magnetic anisotropy than that of said first and second magnetic thin films at room temperature and has a temperature characteristic of the effective anisotropy constant K being convex upward or linear, and having its saturation magnetization M S being from 0 to 450 emu/cm³ at room temperature, comprising the steps of: modulating in accordance with an information signal to be recorded a first heating condition to heat said medium to a temperature T₁ which is virtually above the Curie temperature T C1 of said first magnetic thin film and not causing reversal of the magnetic moment in said second magnetic thin film and a second heating condition to heat the same to a temperature T₂ which is above said temperature T C1 and sufficient to cause reversal of the magnetic moment in said second magnetic thin film; and cooling the medium from the heated states so that record magnetization is formed in said thermomagnetic recording medium.

Claim 5

A thermomagnetic recording method using a thermomagnetic recording medium including a laminated film consisting of a first magnetic thin film formed of a first component film and a second component film, each thereof having perpendicular magnetic anisotropy, a second magnetic thin film having perpendicular magnetic anisotropy, and a third magnetic thin film having in-­plane magnetic anisotropy or small perpendicular magnetic anisotropy interposed between said second component film of said first magnetic thin film and said second magnetic thin film, laminated by being magnetically coupled to the adjoining films in turn, the Curie temperature T C12 of said second component film of said first magnetic thin film being higher than the Curie temperature T C11 of said first component film thereof, comprising the steps of: modulating in accordance with an information signal to be recorded a first heating condition for heating the medium to a temperature T₁ which is in the vicinity of said Curie temperature T C11 , not causing reversal of the magnetic moment in said second magnetic thin film, and sufficient to change the magnetic moment in said second component film of said first magnetic thin film in compliance with the magnetic moment in said second magnetic thin film and a second heating condition for heating the same to a temperature T₂ which is above said Curie temperature T C12 and sufficient to cause reversal of the magnetic moment in said second magnetic thin film; and cooling the medium from the heated states so that record magnetization is formed, in compliance with the magnetization in said second component film of said first magnetic thin film, also in said first component film thereof.

Claim 6

A thermomagnetic recording method using a thermomagnetic recording medium including a laminated film consisting of a first magnetic thin film formed of a first component film and a second component film, each thereof having perpendicular magnetic anisotropy, a second magnetic thin film having perpendicular magnetic anisotropy, and a third magnetic thin film having in-­plane magnetic anisotropy or small perpendicular magnetic anisotropy interposed between said second component film of said first magnetic thin film and said second magnetic thin film, laminated by being magnetically coupled to the adjoining films in turn, the Curie temperature T C12 of said second component film of said first magnetic thin film being higher than the Curie temperature T C11 of said first component film thereof, comprising the steps of: modulating in accordance with an information signal to be recorded a first heating condition for heating the medium to a temperature T₁ which is in the vicinity of said Curie temperature T C11 , not causing reversal of the magnetic moment in said second magnetic thin film, and sufficient to change the magnetic moment in said second component film of said first magnetic thin film in compliance with the magnetic moment in said second magnetic thin film and a second heating condition for heating the same to a temperature T₂ which is above said Curie temperature T C12 and sufficient to cause reversal of the magnetic moment in said second magnetic thin film; and cooling the medium from the heated states so that record magnetization is formed, in compliance with the magnetization in said second component film of said first magnetic thin film, also in said first component film thereof.

Claim 7

A thermomagnetic recording method using a thermomagnetic recording medium including a laminated film having a first magnetic thin film formed of a first component film and a second component film, each thereof having perpendicular magnetic anisotropy, a second magnetic thin film having perpendicular magnetic anisotropy, and a third magnetic thin film having in-­plane magnetic anisotropy or small perpendicular magnetic anisotropy interposed between said second component film of said first magnetic thin film and said second magnetic thin film magnetically coupled to the adjoining films in turn, and further having a magneto-­optical reproducing thin film disposed in the front of said first component film of said first magnetic thin film magnetically coupled thereto, the Curie temperature T C12 of said second component film of said first magnetic thin film being higher than the Curie temperature T C11 of said first component film thereof, said magneto-optical reproducing film satisfying 2M SR h R H CR + 2M S11 h₁₁H C11 < σ wa + 2M S12 h₁₂H C12 (where M SR , M S11 and M S12 ; h R , h₁₁, and h₁₂; H CR , H C11 , and H C12 are saturation magnetization, film thickness, and coercive force of said magneto-­optical reproducing thin film, first, and second component films, respectively, and σ wa is domain wall energy between said second component film and said second magnetic thin film) and having a larger Kerr rotation angle than said first component film, comprising the steps of: modulating in accordance with an information signal to be recorded a first heating condition for heating the medium to a temperature T₁ which is in the vicinity of said Curie temperature T C11 , not causing reversal of the magnetic moment in said second magnetic thin film, and sufficient to change the magnetic moment in said second component film of said first magnetic thin film in compliance with the magnetic moment in said second magnetic thin film and a second heating condition for heating the same to a temperature T₂ which is above said Curie temperature T C12 and sufficient to cause reversal of the magnetic moment in said second magnetic thin film; and cooling the medium from the heated states so that record magnetization is formed, in compliance with the magnetization in said second component film of said first magnetic thin film, also in said first component film thereof and said magneto-optical reproducing thin film.

Claim 8

A thermomagnetic recording method using a thermomagnetic recording medium including a laminated film having a first magnetic thin film formed of a first component film and a second component film, each thereof having perpendicular magnetic anisotropy, a second magnetic thin film having perpendicular magnetic anisotropy, and a third magnetic thin film having in-­plane magnetic anisotropy or small perpendicular magnetic anisotropy interposed between said second component film of said first magnetic thin film and said second magnetic thin film magnetically coupled to the adjoining films in turn, and further having a magneto-­optical reproducing thin film disposed in the front of said first component film of said first magnetic thin film magnetically coupled thereto, the Curie temperature T C12 of said second component film of said first magnetic thin film being higher than the Curie temperature T C11 of said first component film thereof, said magneto-optical reproducing film satisfying 2M SR h R H CR + 2M S11 h₁₁H C11 < σ wa + 2M S12 h₁₂H C12 (where M SR , M S11 and M S12 ; h R , h₁₁, and h₁₂; H CR , H C11 , and H C12 are saturation magnetization, film thickness, and coercive force of said magneto-­optical reproducing thin film, first, and second component films, respectively, and σ wa is domain wall energy between said second component film and said second magnetic thin film) and having a larger Kerr rotation angle than said first component film, comprising the steps of: modulating in accordance with an information signal to be recorded a first heating condition for heating the medium to a temperature T₁ which is in the vicinity of said Curie temperature T C11 , not causing reversal of the magnetic moment in said second magnetic thin film, and sufficient to change the magnetic moment in said second component film of said first magnetic thin film in compliance with the magnetic moment in said second magnetic thin film and a second heating condition for heating the same to a temperature T₂ which is above said Curie temperature T C12 and sufficient to cause reversal of the magnetic moment in said second magnetic thin film; and cooling the medium from the heated states so that record magnetization is formed, in compliance with the magnetization in said second component film of said first magnetic thin film, also in said first component film thereof and said magneto-optical reproducing thin film.

Claim 9

A thermomagnetic recording method using a thermomagnetic recording medium formed in a laminated structure of, at least, fist and second magnetic thin films each having perpendicular magnetic anisotropy, wherein said second magnetic thin film is formed of first and second component films laminated to each other by exchange coupling, said first and second component films having characteristics H C21R > H C22R and T C21 < T C22 , H C21R and H C22R representing coercive forces of said first and second component films at room temperature and T C21 and T C22 representing the Curie temperatures of the same, comprising the steps of: modulating a first heating condition to heat the medium to a first temperature T₁ being virtually in the vicinity of the Curie temperature T C1 of said first magnetic thin film and not causing reversal of the magnetic moment in said second magnetic thin film and a second heating condition to heat the medium to a second temperature T₂ being over said Curie temperature T C1 and sufficient to cause reversal of the magnetic moment in said second magnetic thin film in accordance with an information signal to be recorded, and adapting in the course of the medium cooling down from the first and second heated states such that the magnetic moments within said second magnetic thin film are brought into the same state.

Claim 10

A thermomagnetic recording method using a thermomagnetic recording medium formed in a laminated structure of, at least, fist and second magnetic thin films each having perpendicular magnetic anisotropy, wherein said second magnetic thin film is formed of first and second component films laminated to each other by exchange coupling, said first and second component films having characteristics H C21R > H C22R and T C21 < T C22 , H C21R and H C22R representing coercive forces of said first and second component films at room temperature and T C21 and T C22 representing the Curie temperatures of the same, comprising the steps of: modulating a first heating condition to heat the medium to a first temperature T₁ being virtually in the vicinity of the Curie temperature T C1 of said first magnetic thin film and not causing reversal of the magnetic moment in said second magnetic thin film and a second heating condition to heat the medium to a second temperature T₂ being over said Curie temperature T C1 and sufficient to cause reversal of the magnetic moment in said second magnetic thin film in accordance with an information signal to be recorded, and adapting in the course of the medium cooling down from the first and second heated states such that the magnetic moments within said second magnetic thin film are brought into the same state.