Study of Al interdiffusion in ultrathin β-Ta/Co2FeAl/MgO heterostructures for enhanced spin-orbit torque

Vishal Bhardwaj, Kuan Ming Chen, Yuan Chieh Tseng, Ratnamala Chatterjee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


In this work perpendicular magnetization of Co2FeAl (CFA) full-Heusler alloy films is achieved using rapid thermal annealing under N2/H2 gas flow in Si/β-Ta(6.5 nm)/CFA(0.6–2 nm)/MgO(1.15 nm)/Pd(1 nm) heterostructures. The Al interdiffusion into MgO layer plays an important role in determining perpendicular magnetic anisotropy(PMA) and increasing the damping constant (α) of ultrathin CFA samples. The time of flight SIMS depth profiling along with XPS is used to study interdiffusion of Al across CFA/MgO interface. XPS analysis of Al-2p and Mg-1s spectra indicate the formation of Al2O3 and MgAl2Ox oxide phases at CFA/MgO interface in addition to pure Al metal. The Slonczewski-like and the field-like SOT effective fields are quantified using second harmonics measurements. An effective spin hall angle of β-Ta (6.5 nm) is estimated in range −0.02 to −0.06 for CFA layer thickness varied from 0.8 nm to 1.5 nm.

Original languageEnglish
Article number411662
JournalPhysica B: Condensed Matter
StatePublished - 1 Dec 2019


  • Multilayer thin films
  • PMA
  • Second harmonics technique
  • Spin hall angle
  • XPS

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