Corrosion and/or oxidation damage protection for tunnel junctions

1. A system, comprising:

a magnetic structure having a tunnel junction; and

a controller and logic integrated with and/or executable by the controller, the logic being configured to:

reduce a local relative humidity in a vicinity of the tunnel junction by passing a current through the tunnel junction for at least a period of time that the tunnel junction would otherwise not have a current passing therethrough.

2. A system as recited in claim 1 , the logic being configured to:

determine a relative humidity in an environment of the magnetic structure,

wherein the current is passed through the tunnel junction in response to determining that the relative humidity in the environment of the magnetic structure is above a threshold.

3. A system as recited in claim 1 , the logic being configured to:

determine a relative humidity in an environment of the magnetic structure,

wherein the current is not passed through the tunnel junction in response to determining that the relative humidity in the environment of the magnetic structure is below a threshold.

4. A system as recited in claim 1 , wherein a level of the current is equal to or greater than a normal operation current level.

5. A system as recited in claim 1 , wherein the current is passed through the tunnel junction when the tunnel junction is not in normal use.

6. A system as recited in claim 1 , the logic being configured to:

determine the local relative humidity and a local temperature in a vicinity of the tunnel junction;

calculate a target local temperature in a vicinity of the tunnel junction corresponding to a desired target local relative humidity using the local relative humidity and/or the local temperature; and

determine a level of the current to pass through the tunnel junction based on the desired target local relative humidity and/or the target local temperature.

7. A system as recited in claim 1 , wherein the magnetic structure is a tunnel magnetoresistance read sensor.

8. A system as recited in claim 1 , comprising logic configured to:

measure both an environmental temperature and a relative humidity;

calculate the local relative humidity versus local temperature using a polynomial function from known values of saturation vapor density;

calculate a Joule heating temperature rise required to achieve a particular local relative humidity from the polynomial; and

use the Joule heating temperature rise versus power into the tunnel junction to determine the necessary current through and voltage across the tunnel junction to achieve the particular local relative humidity.

9. A system as recited in claim 1 , wherein the magnetic structure is a magnetic memory element.

10. A method, comprising:

determining a relative humidity in an environment of a tunnel junction that is part of a magnetic structure; and

selecting an operating current from a range of allowable operating currents based on the determined relative humidity;

wherein the selected level of the current is high enough to heat the tunnel junction to a temperature which reduces a local relative humidity in a vicinity of the tunnel junction.

11. A method as recited in claim 10 , wherein the magnetic structure is a tunnel magnetoresistance read sensor.

12. A method as recited in claim 11 , wherein the range of allowable operating currents is limited to operating currents at which the tunnel magnetoresistance read sensor can read data from a magnetic medium.

13. A method as recited in claim 12 , wherein the magnetic medium is a magnetic recording tape.

14. A method as recited in claim 10 , comprising passing a current through the tunnel junction for at least a period of time that the tunnel junction would otherwise not have a current passing therethrough.

15. A method as recited in claim 14 , wherein a level of the current passed through the tunnel junction during the period of time that the tunnel junction would otherwise not have an operating current passing therethrough is higher than the highest allowable operating current.

16. A method as recited in claim 10 , comprising:

determining a temperature in an environment of the magnetic structure;

using the determined relative humidity and the temperature in the environment of the magnetic structure to calculate the local relative humidity and a local temperature in a vicinity of the tunnel junction; and

using the local relative humidity and/or the local temperature in the vicinity of the tunnel junction to determine the level of the current to pass through the tunnel junction.

17. A method as recited in claim 10 , wherein the magnetic structure is a magnetic memory element.