Patent ID: 7224634

Claim:
An array of magnetic memory cells provided with at least one security device, wherein the at least one security device comprises a first magnetic element and a second magnetic element each having a pre-set magnetization direction, the pre-set magnetization direction of the first and second magnetic elements being different from each other, the first and second magnetic elements being suitable for aligning their magnetization direction with magnetic field lines of an externally applied magnetic field, to thereby indicate exposure of the array to said externally applied magnetic field; and a conductor placed over the first magnetic element and the second magnetic element of the security device, the conductor providing a current path for creating an initializing magnetic field to pre-set each magnetization direction of the first and second magnetic element, the initializing magnetic field having a first polarity at the first magnetic element, and a second polarity at the second magnetic element, the second polarity opposite the first polarity.