Abstract
This work reports the development of perpendicular magnetic tunnel junctions, based on a multilayered stack of [Tb/Co] nanolayers, in which the magnetization can be reliably toggled using a single optical pulse. The helicity-independent single-shot switching of the magnetization in the Tb/Co multilayered stack was achieved using either 60 fs-long or 5 ps laser pulses with incident fluences down to 4.7 mJ/cm2. The magnetic switching was achieved for a Co-rich composition window of the multilayer corresponding to layer thickness ratios tCo/tTb between 1.3-1.5. This was confirmed for the multilayer alone as well as for the multilayer coupled to aCoFeB electrode, with a structure consisting of CoFeB/Ta/[Tb/Co]N. The optical switching is preserved even after annealing at 250°C in magnetic tunnel junctions (MTJ) electrodes, exhibiting a tunnel magnetoresistance (TMR) of 41% and RxA value of 150 Ωμm after its integration, measured on unpatterned MTJ stacks. These results represent the first step towards the development of hybrid spintronic photonic systems with fJ switching energies.
Highlights
In a more recent context, it has been demonstrated that Rare earth (RE)-transition metal (TM)-based alloys, such as GdFeCo or TbCo exhibit the phenomena of all-optical switching (AOS),4,5 whereby the magnetization can be reversed using femtosecond- or picosecond-long laser pulses, without the assistance of an external magnetic field
This paper reports the development of a perpendicular magnetic tunnel junction (MTJ), incorporating a [Tb/Co]N-based multilayered stack coupled to a CoFeB layer in order to form the storage layer of a memory MRAM
The increase of the coercive field as the composition approaches the 1:1 tCo/tTb thickness ratio indicates that the magnetic moment compensation of the Co and Tb sublattices at room temperature occurs in the central part of the composition region
Summary
Rare earth (RE)- transition metal (TM) alloys and multilayers have been extensively studied due to their potential application in several fields of magnetism, being of particular importance in the field of magneto-optical recording. The magnetic properties of RE-TM thin films, both in amorphous alloy forms and as a multilayered structures have been explored in detail, and previous works have highlighted their strong perpendicular magnetic anisotropy (PMA) and the possibility to tune the anisotropy constant by varying the relative proportions of the TM and RE constituents. In a more recent context, it has been demonstrated that RE-TM-based alloys, such as GdFeCo or TbCo exhibit the phenomena of all-optical switching (AOS), whereby the magnetization can be reversed using femtosecond- or picosecond-long laser pulses, without the assistance of an external magnetic field. In a more recent context, it has been demonstrated that RE-TM-based alloys, such as GdFeCo or TbCo exhibit the phenomena of all-optical switching (AOS), whereby the magnetization can be reversed using femtosecond- or picosecond-long laser pulses, without the assistance of an external magnetic field. AOS can be classified, depending on the necessary properties of the laser pulses, as helicity-dependent (AO-HDS) or helicity-independent (AO-HIS). These effects have been observed to induce magnetization reversal in different materials either with a single pulse or with multiple consecutive pulses. This paper reports the development of a perpendicular MTJ, incorporating a [Tb/Co]N-based multilayered stack coupled to a CoFeB layer in order to form the storage layer of a memory MRAM. It is known that RE-TM systems are sensitive to post-deposition annealing. we demonstrate that the PMA is preserved after annealing at 250○C and the capacity for single-shot all-optical switching is conserved
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