An array of memory cells, each cell comprising a first and second ferromagnetic layers that form either a spin valve or a magnetic tunnel junction; at least one conductor operatively connected to at least one of the first and second ferromagnetic layers; a third ferromagnetic layer magnetically coupled to the second magnetic layer having permittivity which changes from a first state to a second state of lower permittivity upon heating; the second ferromagnetic layer being influenced by the permittivity of the third ferromagnetic layer; and a heater element operatively associated with the third magnetic layer which selectively provides heat to the third magnetic layer to change its permittivity. An alternate embodiment comprises an array of cells, each cell comprising a ferromagnetic region having permittivity which changes from a first state to a second state upon heating and a heater operatively which selectively provides heat to the third magnetic layer.