Thermally-assisted magnetic recording head including first and second cladding sections having different characteristics

1. A thermally-assisted magnetic recording head, comprising:

a waveguide;

a magnetic pole;

a cladding layer provided between the waveguide and the magnetic pole; and

a plasmon generator embedded in the cladding layer, wherein

the cladding layer includes a first cladding section located on a side close to an air-bearing surface and a second cladding section located on a side far from the air-bearing surface, and

a thermal expansion coefficient of the first cladding section is larger than a thermal expansion coefficient of the second cladding section.

2. The thermally-assisted magnetic recording head according to claim 1 , wherein a compression stress of the first cladding section is smaller than a compression stress of the second cladding section.

3. The thermally-assisted magnetic recording head according to claim 1 , wherein a forming material of the first cladding section is different from a forming material of the second cladding section.

4. The thermally-assisted magnetic recording head according to claim 1 , wherein the plasmon generator includes a metal material, and the cladding layer includes a dielectric material.

5. The thermally-assisted magnetic recording head according to claim 1 , wherein

the plasmon generator includes one or more of gold (Au), silver (Ag), copper (Cu), and aluminum (Al),

the first cladding section includes magnesium oxide (MgO) or zirconium oxide (ZrO 2 ) or both, and

the second cladding section includes one or more of silicon oxide (SiO x ), aluminum oxide (Al 2 O 3 ), and silicon oxynitride (SiO x N y ).

6. The thermally-assisted magnetic recording head according to claim 1 , wherein the plasmon generator includes

a first plasmon generator section located on the side close to the air-bearing surface, and

a second plasmon generator section located on the side far from the air-bearing surface and having a width larger than a width of the first plasmon generator section, and

a position of back end in the first cladding section is substantially coincident with a position of back end of the first plasmon generator section, or is located at backward of the position of back end in the first plasmon generator.

7. The thermally-assisted magnetic recording head according to claim 1 , wherein

the first cladding section extends backward from the air-bearing surface, and

a distance from the air-bearing surface to a position of back end of the first cladding section is from about 50 nanometers to about 100 nanometers both inclusive.

8. A head gimbal assembly, comprising:

a magnetic head slider having a side surface, the side surface being provided with the thermally-assisted magnetic recording head according to claim 1 ; and

a suspension having an end, the end being attached with the magnetic head slider.

9. A head arm assembly, comprising:

a magnetic head slider having a side surface, the side surface being provided with the thermally-assisted magnetic recording head according to claim 1 ;

a suspension having a first end and a second end, the first end being attached with the magnetic head slider; and

an arm supporting the suspension at the second end thereof.

10. A magnetic recording unit provided with a magnetic recording medium and a head arm assembly, the head arm assembly comprising:

a magnetic head slider having a side surface, the side surface being provided with the thermally-assisted magnetic recording head according to claim 1 ;

a suspension having a first end and a second end, the first end being attached with the magnetic head slider; and

an arm supporting the suspension at the second end thereof.