VCMA effect relies on electric field induced change of atomic orbital occupancy at interface. This change is in synchronic connection with spin-orbital interaction, which consequently results in the change of anisotropy []. A qualitative explanation based on Rashba effect also has been given for VCMA, which relies on the Dzyaloshinskii–Moriya mechanism[]. In 2010, electric field effects on thickness dependent magnetic properties of CoFeB layers was investigated at room temperature. This study demonstrated the electric field manipulation of magnetic anisotropy in in-plane 2 nm thick CoFeB. On the other hand, for 1.16 nm and 1.02 nm thick perpendicularly magnetized CoFeB electric field induced alteration of coercivity was observed []. Wang in 2012 demonstrated the et al. switching in perpendicular MTJs []. The usual MTJs have thick ferromagnetic layers (>3 nm), where the magnetic anisotropy is independent of the ferromagnetic barrier oxide layer interface [, , , ]. The electric field effect in these layers is negligible due to the screening of electrons. In the case of electric field assisted switching, the thickness of CoFeB is relatively thin (1.6 nm). For this thickness, the PMA arises from the oxide layer interface. As a result of the applied field, the interface anisotropy is affected and the magnetic orientation is changed [, ]. The main advantage of using the VCMA based memory is the dramatic reduction in power dissipation. By reducing the required current to operate the device, Ohmic dissipation is significantly reduced, which in most cases of magnetic memory, is the predominant loss mechanism [, ]. Contrary to STT-MRAM for which the pulse polarity determines the switching direction, the write process in VCMA based memory is only one write pulse amplitude and width is used to achieve both 0-to-1 and 1-to-0 switching. Hence, a pre-read step is required to determine the initial state (0 or 1) before writing. On the other hand, the barrier being voltage dependent, reading error
VCMA effect relies on electric field induced change of atomic orbital occupancy at interface. This change is in synchronic connection with spin-orbital interaction, which consequently results in the change of anisotropy []. A qualitative explanation based on Rashba effect also has been given for VCMA, which relies on the Dzyaloshinskii–Moriya mechanism[]. In 2010, electric field effects on thickness dependent magnetic properties of CoFeB layers was investigated at room temperature. This study demonstrated the electric field manipulation of magnetic anisotropy in in-plane 2 nm thick CoFeB. On the other hand, for 1.16 nm and 1.02 nm thick perpendicularly magnetized CoFeB electric field induced alteration of coercivity was observed []. Wang et al. in 2012 demonstrated the switching in perpendicular MTJs []. The usual MTJs have thick ferromagnetic layers (>3 nm), where the magnetic anisotropy is independent of the ferromagnetic barrier oxide layer interface [, , , ]. The electric field effect in these layers is negligible due to the screening of electrons. In the case of electric field assisted switching, the thickness of CoFeB is relatively thin (1.6 nm). For this thickness, the PMA arises from the oxide layer interface. As a result of the applied field, the interface anisotropy is affected and the magnetic orientation is changed [, ]. The main advantage of using the VCMA based memory is the dramatic reduction in power dissipation. By reducing the required current to operate the device, Ohmic dissipation is significantly reduced, which in most cases of magnetic memory, is the predominant loss mechanism [, ]. Contrary to STT-MRAM for which the pulse polarity determines the switching direction, the write process in VCMA based memory is only one write pulse amplitude and width is used to achieve both 0-to-1 and 1-to-0 switching. Hence, a pre-read step is required to determine the initial state (0 or 1) before writing. On the other hand, the barrier being voltage dependent, reading error
MRAM_Review_Ver1_Mat_Today.docx