Thermally-assisted magnetic recording device, thermally-assisted magnetic reproducing device and electron beam recorder

Abstract

Electrons are directed from an electron emitter towards a magnetic recording medium to heat a recording portion of the magnetic recording medium and magnetic information is written by a magnetic recording head to the temperature-elevated recording portion. Otherwise, a magnetic head having a magnetic pole is used and the magnetic pole serves as an electron emitter as well. Alternatively, a space between the electron emitter and recording medium is made shorter smaller the mean free path of electrons in the atmosphere to considerably improve the recording density.

What is claimed is:  
     
         1 . A thermally-assisted magnetic recording device comprising: 
 an electron emitter configured to. emit electrons toward a magnetic recording medium for heating a recording portion of the magnetic recording medium to decrease a coercive force; and    a magnetic pole configured to apply a magnetic field to the magnetic recording medium to record an information magnetically to the recording portion decreased in coercive force.    
     
     
         2 . The thermally-assisted magnetic recording device according to  claim 1 , wherein the electron emitter heats the magnetic recording medium so that a coercive force of the recording portion of the magnetic recording medium becomes smaller than an intensity of the magnetic field developed at the recording portion by the magnetic pole.  
     
     
         3 . The thermally-assisted magnetic recording device according to  claim 1 , wherein at an ambient temperature, the recording portion of the magnetic recording medium has a larger coercive force than the intensity of the magnetic field developed by the magnetic pole.  
     
     
         4 . The thermally-assisted magnetic recording device according to  claim 1 , further comprising a driving mechanism configured to move the magnetic recording medium in relation to the electron emitter and the magnetic pole, wherein the electron emitter is provided at a leading side of the direction of the movement by the driving mechanism and the magnetic pole is provided at a trailing side of the direction of the movement by the driving mechanism.  
     
     
         5 . The thermally-assisted magnetic recording device according to  claim 4 , wherein the electron emitter includes a plurality of electron emitting portions disposed along a direction of the movement thereof by the driving mechanism.  
     
     
         6 . The thermally-assisted magnetic recording device according to  claim 4 , wherein a recording track parallel to the moving direction is formed on the magnetic recording medium; and a length Te of the electron emitter in a width direction of the recording track and a length Tw of the magnetic pole in a width direction of the recording track are in a relation of Te/2≦Tw≦2Te with each other.  
     
     
         7 . The thermally-assisted magnetic recording device according to  claim 1 , wherein the electron emitter emits the electrons by field emission.  
     
     
         8 . The thermally-assisted magnetic recording device according to  claim 1 , wherein the electron emitter emits the electrons in a non-oxidizing atmosphere or depressurized atmosphere.  
     
     
         9 . The thermally-assisted magnetic recording device according to  claim 8 , the oxygen partial pressure X (in mols/cm 3 ) and emission electron current density J (in A/cm 2 ) of around the electron emitter are in relations of X≦1.25×10 12 ×J and J≦10 4  with each other.  
     
     
         10 . A thermally-assisted magnetic recording device comprising: 
 a recording magnetic pole configured to apply a magnetic field to a magnetic recording medium; and    a lead connected to the magnetic pole;    wherein a voltage is applied to the lead to allow the magnetic pole to emit electrons with which a recording portion of the magnetic recording medium is heated, and information is recorded magnetically to the magnetic recording medium by applying the recording portion with a magnetic field from the magnetic pole.    
     
     
         11 . The thermally-assisted magnetic recording device according to  claim 10 , wherein the mean value of the surface roughness of the magnetic pole opposite to the magnetic recording medium is over 0.5 nm and under 10 nm.  
     
     
         12 . The thermally-assisted magnetic recording device according to  claim 10 , further comprising a return-path magnetic pole forming a magnetic circuit for the magnetic field with the magnetic pole and magnetic recording medium; 
 the return-path magnetic pole being located as recessed from the magnetic pole as viewed from the magnetic recording medium.    
     
     
         13 . The thermally-assisted magnetic recording device according to  claim 10 , further comprising a return-path magnetic pole forming a magnetic circuit for the magnetic field with the magnetic pole and magnetic recording medium, 
 a mean value of the surface roughness of the return-path magnetic pole opposite to the magnetic recording medium being smaller than a mean value of the surface roughness of the magnetic pole opposite to the magnetic recording medium.    
     
     
         14 . The thermally-assisted magnetic recording device according to  claim 10 , wherein the magnetic pole has at least a projection provided on a surface thereof opposite to the magnetic recording medium.  
     
     
         15 . A thermally-assisted magnetic reproducing device comprising: 
 a magnetic yoke;    a lead connected to the magnetic yoke; and    a magnetic reproducing element magnetically coupled to the magnetic yoke;    wherein a voltage is applied to the lead to allow the magnetic yoke to direct electrons towards a magnetic recording medium to heat the magnetic recording medium, and information is reproduced from the magnetic recording medium by guiding a magnetic field from the magnetic recording medium to the magnetic reproducing element via the magnetic yoke.    
     
     
         16 . The thermally-assisted magnetic reproducing device according to  claim 15 , wherein a mean value of the surface roughness of the magnetic yoke opposite to the magnetic recording medium is over 0.5 nm and under 10 nm.  
     
     
         17 . The thermally-assisted magnetic reproducing device according to  claim 15 , further comprising a driving mechanism to move the magnetic recording medium in relation to the magnetic yoke; 
 the magnetic yoke including a first magnetic yoke provided at a leading side of the direction of the movement by the driving mechanism and a second magnetic yoke provided at a trailing side; and    the second magnetic yoke being located as recessed from the first magnetic yoke as viewed from the magnetic recording medium.    
     
     
         18 . The thermally-assisted magnetic reproducing device according to  claim 15 , further comprising a driving mechanism to move the magnetic recording medium in relation to the magnetic yoke; 
 the magnetic yoke including a first magnetic yoke provided at a leading side of the direction of the movement by the driving mechanism and a second magnetic yoke provided at a trailing side; and    a mean value of a surface roughness of the second magnetic yoke opposite to the magnetic recording medium being smaller than a mean value of a surface roughness of the first magnetic yoke opposite to the magnetic recording medium.    
     
     
         19 . The thermally-assisted magnetic reproducing device according to  claim 15 , wherein the magnetic yoke has at least a projection provided on a surface thereof opposite to the magnetic recording medium.  
     
     
         20 . An electron beam recording device comprising an electron emitter configured to emit electrons towards a recording medium in a gas atmosphere at a substantial atmospheric pressure to heat the recording medium and to record information to the recording medium, 
 wherein the electron emitter and recording medium being spaced from each other by a distance shorter than the mean free path of the electrons emitted from the electron emitter.    
     
     
         21 . The electron beam recording device according to  claim 20 , wherein the electron emitter emits electrons by field emission.  
     
     
         22 . The electron beam recording device according to  claim 20 , wherein the electron emitter has a surface layer formed mainly from carbon.  
     
     
         23 . The electron beam recording device according to  claim 20 , wherein when a spacing d (in nm) between the electron emitter and recording medium meets the following condition: 
         d <λmin×(760 /P ) 
       where λmin is the minimum value (in nm) of the mean free path of the electrons at 1 atm. and P is the pressure (in Torr) of the gas atmosphere.  
     
     
         24 . The electron beam recording device according to  claim 20 , wherein the recording medium has a recording layer whose optical characteristic changes as it is heated.