A CoFeB/MgO/CoFeB perpendicular magnetic tunnel junction coupled to an in-plane exchange-biased magnetic layer

Abstract

We report a stack structure which utilizes an in-plane exchange-biased magnetic layer to influence the coercivity of the bottom CoFeB layer in a CoFeB/MgO/CoFeB perpendicular magnetic tunnel junction. By employing a thickness wedge deposition technique, we were able to study various aspects of this stack using vibrating sample magnetometer including: (1) the coupling between two CoFeB layers as a function of MgO thickness; and (2) the coupling between the bottom CoFeB and the in-plane magnetic layer as a function of Ta spacer thickness. Furthermore, modification of the bottom CoFeB coercivity allows one to measure tunneling magnetoresistance and resistance-area product (RA) of CoFeB/MgO/CoFeB in this pseudo-spin-valve format using current-in-plane-tunneling technique, without resorting to (Co/Pt)n or (Co/Pd)n multilayer pinning.

Tailoring magnetization and anisotropy of tetragonal Mn3Ga thin films by strain-induced growth and spin orbit coupling

“…This difference is likely originated from IP tensile deformation and contraction of the cell along the c axis [26]. This suggestion is valid for strained Mn 3 Ga layers grown on Cr where To further try to explain this issue in our samples we focus our explanation on the magnetic coupling at the interface between Mn 3+ -3d 4 and Mo-5s 1 4d 5 orbitals inducing IP oriented domains. The valence state of Mn 3+ with d 4 occupancy is found on Mn atoms octahedrally coordinated [29].…”

“…One of the most successful applications of materials sciences in spintronics is the construction of magnetic random access memories (MRAM), whose principal feature is its non-volatile capacity to store information [1][2][3]. The core of a MRAM is a magnetic tunnel junction (MTJ) where the writing process consists on switching the magnetic orientation of the free layer [4][5][6]. A practical method for this purpose, which simplifies the architecture of the MRAM [7], is the use of the spin-transfer torque (STT) phenomenon consisting on the magnetization or magnetization reversal of the free layer by the injection of a spin polarized pulse [8,9].…”

Nanoscale Spin-Transfer Torque MRAM Etching Using Various Gases

“…Among them, spin transfer torque magnetic random access memory (STT-MRAM) has received a lot of attention because of its very high speed of device, endurance, low power consumption of device, and high density memory cell in addition to the non-volatility of information [3,4]. Especially, the MTJ memory elements which consist of CoxFeyBz/MgO/CoxFeyBz multilayer structure are the critical building blocks for high density magnetic random access memory with high tunneling magnetoresistance (TMR) [5][6][7]. However, the dry etching of MTJ stack with sub 70 nm is a challenging step in the fabrication of STT-MRAM [8].…”