Modulated switching current density and spin-orbit torques in MnGa/Ta films with inserting ferromagnetic layers

Abstract

We report modulated switching current density and spin-orbit torques (SOT) in MnGa/Ta films with inserting very thin Co2FeAl and Co layers. Ferromagnetic coupling has been found in MnGa/Co2FeAl/Ta, resulting in a decreased effective anisotropy field. On the contrary, in MnGa/Co/Ta, antiferromagnetic coupling plays a dominant role. The switching current density Jc in MnGa/Ta is 8.5 × 107 A/cm2. After inserting 0.8-nm-thick Co2FeAl and Co, theJc becomes 5 × 107 A/cm2 and 9 × 107 A/cm2, respectively. By performing adiabatic harmonic Hall voltage measurements, it is demonstrated that the inserted Co2FeAl layer has mainly enhanced the field-like torques, while in MnGa/Co/Ta the damping-like torques have been enhanced. Finally, the enhanced spin Hall effect (SHE) has also been studied using the spin Hall magnetoresistance measurement. The modulated Jc and SOT are ascribed to the combination of magnetic coupling, Rashba effect and SHE at the interfaces.

2D V‐V Binary Materials: Status and Challenges

“…At room temperature, BiSb/MnGa bilayer holds a large spin Hall angle of 52, which is the highest value reported so far. An ultralow current density is observed in BiSb/MnGa bilayers, only J = 1.5 × 10 6 Α cm −2 , much lower than that of Ta/MnGa, IrMn/MnGa, Pt/MnGa . The average electrical conductivity of BiSb reaches to 2.5 × 10 5 Ω −1 m −1 .…”

Anomalous Hall effect in MnAl/W bilayers: Modification from strong spin Hall effect of W

“…2(c) The small M S of the MnAl film studied here indicates a very low degree of spin population imbalance with the loss of the chemical ordering. This could be the reason why the ferromagnetic exchange splitting does not quench the 2CK physics [31].…”

“…The spin currents that diffuse into the FM will modify the spin dependent transport properties such as AHE [23]. On the other hand, the spin currents will also exert torque on the magnetization, which is similar to spin transfer torque [24][25][26][27][28][29][30][31]. Considering the essence of AHE, the modification from SHE can also be explored through clarifying    xx relations [23].…”

Spin Hall Effect in Topological Insulators

“…The threshold switching current density is only 1.5 × 10 6 Acm −2 , which is smaller than that of MnGa/Pt,Ta,IrMn bilayers by two orders of magnitude. [35][36][37] Figure 8 shows the expected writing current and writing energy of a realistic SOT-MRAM device using various type of materials for the pure spin current source, including heavy metals, two-dimensional materials, and topological insulators. 38) It can be seen that our MBE-grown BiSb outperformed all other materials by several orders of magnitude, because BiSb shows not only high electrical conductivity but also a giant spin Hall angle.…”