Large Perpendicular Magnetic Anisotropy and Voltage Controlled Magnetic Anisotropy Effects at CoFe/MgO Interface

The ongoing thrust in big data mining and artificial intelligence is critically demanding the high-density and fast access data storage, which cannot be fulfilled with current computation architecture due to the slow access speed of memory. Using the nonvolatile memory (NVM) element with high density and high speed can potentially tackle this impasse in the journey of next-generation computing [1] . Among several others, magnetic random-access memory (MRAM) is one of the promising NVM elements [2] . The basic building block of MRAM is a magnetic tunnel junction (MTJ), where the resistance state of the device can be modulated by manipulating the spin state of the magnetic layers via the current or magnetic field. Magnetization manipulation by voltage is an attractive alternative as it reduces the energy consumption by orders of magnitude with faster write/read operation and provides a higher density memory solution compared with current-controlled devices. The common route to use the voltage for this purpose is by exploiting the voltage-controlled magnetic anisotropy (VCMA) effect at the magnetic layer/ MgO interface [3] . Upon the application of voltage, the modification of the electronic occupation states of the d orbitals of the ferromagnetic electrode at the interface modulates the magnetic anisotropy. Additionally, the electric field-induced magnetic dipole moment and the Rashba effect are also proposed mechanisms for the origin of the VCMA effect [4] . In addition to the large VCMA effect for the writing operation, high perpendicular magnetic anisotropy (PMA) is required for thermal stability of data retention in MRAM devices [5] . The enhancement in PMA and VCMA effect in the CoFe/MgO system has resulted from the insertion of a thin metallic dusting layer (e.g. Ir, Mg, Pd, Hf) at the CoFe/MgO interface but at the expense of reducing magnetic moment [6] . In this work, we have demonstrated a large enhancement in PMA, the coercive field of the CoFe layer, and the VCMA effect with the insertion of thin, novel metallic dusting layers between CoFe and MgO layers without any reduction in magnetic moment. These results demonstrate that the engineering of the ferromagnet/MgO interface with the insertion of a suitable metallic dusting layer can provide a pathway to develop high-density voltage-driven spintronic devices.