Temperature dependent coercivity crossover in pseudo-spin-valve magnetic tunnel junctions with perpendicular anisotropy

Abstract

We report the temperature dependent collapse of tunnel magnetoresistance (TMR) in perpendicular anisotropy magnetic tunnel junctions (pMTJs) with AlO x barriers and (Co/Pt) 3 multilayer electrodes, due to the coercivity crossover of the top and bottom (Co/Pt) 3 stacks. The different temperature dependence of two (Co/Pt) 3 stacks in pMTJs is mainly caused by the additional perpendicular anisotropy created at interface between the ferromagnetic electrode and the AlO x barrier.

Materials with perpendicular magnetic anisotropy for magnetic random access memory

“…Co/Pd and Co/Pt multilayers grow with (111) fcc structure on selected seedlayers such as Ta, Pd, Pt or Ru. So far, MTJ based on amorphous AlOx with Co/Pt as soft and hard layers showed a relatively low TMR of about 25% in the best case 37–40. This is mainly due to the low spin polarization of the Co/Pt multilayer compared to CoFe or CoFeB alloys as a consequence of the insertion of Pt or Pd non‐magnetic layer.…”

Origin of the collapse of tunnel magnetoresistance at high annealing temperature in CoFeB/MgO perpendicular magnetic tunnel junctions

“…We note that there is no competing perpendicular anisotropies in the present CoFeB/MgO system, and thus, the situation is somewhat different from the (Co/Pt) 3 / AlO x -based p-MTJs with two interfacial anisotropies, which show also the T dependent collapse of the TMR ratio. 23 The existence of dipolar interlayer coupling reduces the switching field of the top CoFeB layer and increases that of the bottom CoFeB layer from their original values in the absence of the coupling, because the coupling favors a parallel M configuration. Thus, the coupling reduces the difference between H C1 and H C2 , and promotes their overlap at higher temperatures.…”

Study on lattice symmetry of sputtered Co–Cu–Pt metastable ordered thin films

“…Typically, multilayers that induce perpendicular interface anisotropy, such as Co/Pt [1], CoFe/Pd [2] and others, have been widely adopted as fixed and/or free layers in those devices, because they can be fabricated at room-temperature (RT). However, to achieve PMA and uniform magnetic properties in those multilayers, a complex preparation process with precisely controlled deposition parameters is required, reducing their range of practical applications.…”