Low thermal coefficient of resistivity on-slider tunneling magneto-resistive shunt resistor
A slider includes a Tunneling Magneto-Resistive (TuMR) read sensor and a shunt resistor connected in parallel. The shunt resistor may be located in a read structure of the slider. The shunt resistor may reduce a total resistance of the read structure and any corresponding impedance mismatch between the read structure, a transmission line, and a preamplifier. The shunt resistor may be made of a material having a near zero thermal coefficient of resistivity (TCR) to test a quality of the TuMR read sensor. The TuMR read sensor may be deemed defective if its TCR deviates from a population average by a specific criterion. The TuMR read sensor may include a MgO tunneling barrier to improve signal strength. The TuMR read sensor may include a free layer that is able to be saturated with a perpendicular background field to calculate a more accurate TCR of the TuMR read sensor.
1. A slider comprising:
a tunneling magneto-resistive (TuMR) read sensor; and
a shunt resistor connected in parallel to the TuMR read sensor for at least partially reducing a total resistance of a read structure of the slider;
wherein the shunt resistor is made of a material having a near zero thermal coefficient resistivity (TCR) and a resistivity of about 20 μΩcm or less.
2. The slider of claim 1 ,
wherein the shunt resistor is made of a material having a TCR where the absolute value of the TCR is less than about 0.2%/° C.
3. The slider of claim 2 ,
wherein the shunt resistor is made of a material having a negative TCR.
4. The slider of claim 1 ,
wherein the shunt resistor is located in a head part of the slider.
5. The slider of claim 1 ,
wherein a total resistance value (R T ) of the read structure of the slider is based on a parallel combination of a shunt resistance value (R S ) of the shunt resistor and a TuMR resistance value (R TuMR ) of the TuMR read sensor.
6. The slider of claim 1 ,
wherein the read structure of the slider is configured for use with a transmission line and a preamplifier; and
wherein the shunt resistor is configured to reduce an impedance mismatch between the read structure of the slider the transmission line, and the preamplifier.
7. The slider of claim 1 , further comprising:
a heat source for raising a temperature of the read structure by a known elevation.
8. The slider of claim 7 ,
wherein the heat source comprises one of a fly height adjustment (FHA) heater and a write coil.
9. The slider of claim 1 , the TuMR read sensor comprising:
at least a free layer;
at least a pinned layer; and
at least a tunneling layer located between the free layer and the pinned layer.
10. The slider of claim 9 ,
wherein the tunneling layer comprises MgO.
11. The slider of claim 1 , the read structure of the slider further comprising:
at least two read shields for at least partially shielding the TuMR read sensor from stray magnetic fields;
wherein the TuMR read sensor is located at least partially between the at least two read shields; and
wherein the shunt resistor is located at least partially adjacent to at least one of the at least two read shields.
12. The slider of claim 11 ,
wherein at least one of the at least two read shields is located at least partially between the TuMR read sensor and the shunt resistor.
13. The slider of claim 1 , wherein the shunt resistor is formed of a material selected from the group consisting of Cu 96.5 Mn 3.5 , Ni 80 Fe 20 , Cu 88 Sn 12 , Cu 95 Sn 5 , Cu 91 Mn 7 Fe 2 , Au 67 Cu 15 Ag 18 and Au 67 Ag 33 .
14. A sensing system, comprising:
a tunneling magneto-resistive (TuMR) read sensor; and
a shunt resistor connected in parallel to the TuMR read sensor;
wherein:
the shunt resistor is made of a material having a near zero thermal coefficient of resistivity (TCR);
the TuMR read sensor is located at least partially between a first read shield and a second read shield;
the first read shield and the second read shield allow for at least partially shielding the TuMR read sensor from stray magnetic fields; and
the shunt resistor is located outside of an area that is between the first read shield and the second read shield.
15. The sensing system of claim 14 ,
wherein the TuMR read sensor is included in a read structure; and
wherein the shunt resistor at least partially reduces a total resistance of the read structure.
16. The sensing system of claim 14 ,
wherein the shunt resistor is made of a material having a particular TCR; and
wherein an absolute value of the particular TCR is less than about 0.2%/° C.
17. The sensing system of claim 14 ,
wherein the shunt resistor is made of a material having a negative TCR.
18. The sensing system of claim 14 , wherein the TuMR read sensor comprises:
a free layer;
a pinned layer; and
a tunneling layer located between the free layer and the pinned layer.
19. The sensing system of claim 18 ,
wherein the tunneling layer comprises MgO.
20. The sensing system of claim 14 , wherein:
the TuMR read sensor and the shunt resistor are incorporated in a read structure of a disk drive; and
a total resistance value of the read structure is based on a parallel combination of a shunt resistance value of the shunt resistor and a particular resistance value of the TuMR read sensor.
21. The sensing system of claim 20 ,
wherein the disk drive further includes:
a transmission line; and
a preamplifier connected to the transmission line; and
wherein the read structure is connected to the transmission line.
22. The sensing system of claim 21 ,
wherein the shunt resistor is configured to reduce an impedance mismatch between the read structure, the transmission line, and the preamplifier.
23. The sensing system of claim 21 , wherein the disk drive further includes:
a heat source for raising a temperature by a predetermined amount.
24. The sensing system of claim 23 ,
wherein the heat source comprises one of a fly height adjustment (FHA) heater and a write coil.
25. The sensing system of claim 14 ,
wherein at least one of the first read shield and the second read shield is located at least partially between the TuMR read sensor and the shunt resistor.
26. The sensing system of claim 14 , wherein the shunt resistor is formed of a material selected from the group consisting of Cu 96.5 Mn 3.5 , Ni 80 Fe 20 , Cu 95 Sn 12 , Cu 95 Sn 5 , Cu 91 Mn 7 Fe 2 , Au 67 Cu 15 Ag 18 and Au 67 Ag 33 .
27. A slider comprising:
a tunneling magneto-resistive (TuMR) read sensor;
a shunt resistor connected in parallel to the TuMR read sensor for at least partially reducing a total resistance of a read structure of the slider, wherein the shunt resistor is made of a material having a near zero thermal coefficient resistivity (TCR); and
at least two read shields for at least partially shielding the TuMR read sensor from stray magnetic fields;
wherein:
the TuMR read sensor is located at least partially between the at least two read shields;
the shunt resistor is located at least partially adjacent to at least one of the at least two read shields; and
at least one of the at least two read shields is located at least partially between the TuMR read sensor and the shunt resistor.
28. The slider of claim 27 ,
wherein the shunt resistor is made of a material having a TCR, the absolute value of which is less than about 0.2%/° C.
29. The slider of claim 27 , wherein the shunt resistor is formed of a material having a resistivity of about 20 μΩcm or less.
30. The slider of claim 27 , wherein the shunt resistor is formed of a material selected from the group consisting of Cu 96.5 Mn 3.5 , Ni 80 Fe 20 , Cu 88 Sn 12 , Cu 95 Sn 5 , Cu 91 Mn 7 Fe 2 , Au 67 Cu 15 Ag 18 and Au 67 Ag 33 .