Improved switching performance of magnetic tunnel junctions with Heusler compounds by insertion of resistive layers

The chemical templating layer (CTL) is ideally suited to grow ordered multicomponent Heusler compounds at temperatures compatible with complementary metal–oxide–semiconductor technology and at thickness necessary for their implementation as storage layers in magnetic random-access memory (MRAM). In current MRAM technology, the storage layer is either capped or seeded with oxide layers (i.e., sandwiched between two resistive layers), primarily to suppress effective Gilbert damping. The CTL, which is metallic and in contact with the storage layer, is expected to enhance the effective damping constant of the Heusler compound due to spin-pumping effect leading to a high switching current. We demonstrate two approaches to mitigate this by inserting ultrathin resistive layers of either MgO or ScN in proximity to the CTL/Heusler interface. The ∼4 Å-thick MgO layer is discontinuous, containing voids filled with CTL that transfers templating information from the underlying thick CTL layer to the Heusler compound. The ScN layer is thick (∼50 Å) and promotes ordering in the Heusler compound via an ultrathin CTL layer (∼20 Å). The magnetic tunnel junction devices with such resistive layers have higher efficiency and operate at lower switching currents.