Spin-transfer torque switching in magnetic tunnel junctions and spin-transfer torque random access memory

Abstract

We present experimental and numerical results of current-driven magnetization switching in magnetic tunnel junctions. The experiments show that, for MgObased magnetic tunnelling junctions, the tunnelling magnetoresistance ratio is as large as 155% and the intrinsic switching current density is as low as 1.1 × 10 6 A cm −2. The thermal effect and current pulse width on spin-transfer magnetization switching are explored based on the analytical and numerical calculations. Three distinct switching modes, thermal activation, dynamic reversal, and precessional process, are identified within the experimental parameter space. The switching current distribution, write error, and read disturb are discussed based on device design considerations. The challenges and requirements for the successful application of spin-transfer torque as the write scheme in random access memory are addressed.

TEAM: ThrEshold Adaptive Memristor Model

“…STT-MRAM exhibits these characteristics except for the high on/off resistance ratio [11]. To design and analyze memristor-based circuits and applications, a model exhibiting these traits is required.…”

“…Equation (11) is illustrated in Figure 8 for the measured fitting parameters reported in [18]. The physical phenomena behind the behavior shown in (11) are not yet fully understood, but considered to be a mixture of nonlinear drift at high electric fields and local Joule heating enhancing the oxygen vacancies. In practical memristors, the ON switching is significantly faster than the OFF switching because of the diffusion of the oxygen vacancies from TiO 2-x to TiO 2 , and the drift of the oxygen vacancies due to the internal electric field is different for positive and negative voltages.…”

“…As mentioned in section IV-B, f off (x) and f on (x) are window functions, or alternatively, functions that fit the Simmons tunnel barrier model based upon the separation of variables of (11). These functions represent the dependence of the derivative in the state variable x.…”

Novel Self-Reference Sense Amplifier for Spin-Transfer-Torque Magneto-Resistive Random Access Memory

“…In precesional region, required current increases dramatically to reduce the switching time, and in thermal assisted region, required current slowly increases while reducing the switching time. Proposed PRSA use the characteristic that the switching time can be controlled by adjusting the amount of current through MTJ [6,7]. arrays, Write Driver (WD), input node, sense amplifier (SA), control driver (CD) and output node.…”

Tailoring of magnetic properties of ultrathin epitaxial Fe films by Dy doping

“…C Control of the static and dynamic magnetic properties of high-quality ferromagnetic (FM) thin films is essential for the development of spintronic devices utilizing spin-transfer torque. [1][2][3] One attractive route to achieve control of the damping parameters is through the use of rare earth (RE) dopants, which couple antiferromagnetically to the host FM lattice, 4 leading to a reduction in saturation magnetization (M s ). 5,6 More importantly, the damping parameter of the film can be significantly enhanced by relatively low doping concentrations, on the order of 10%.…”