The impact of Hf layer thickness on the perpendicular magnetic anisotropy in Hf/CoFeB/MgO/Ta films

Minghua Li*, Jinhui Lu, Mustafa Akyol, Xi Chen, Hui Shi, Gang Han, Tong Shi, Guanghua Yu, Ahmet Ekicibil, Nick Kioussis, P. V. Ong, Pedram Khalili Amiri, Kang L. Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

The impact of Hf layer thickness on magnetic anisotropy is evaluated for Hf/CoFeB/MgO/Ta multilayer films commonly used in magnetic tunnel junctions (MTJs). An easy-axis magnetization transition from the in-plane to the out-of-plane direction is observed when the thickness of Hf is greater than ∼1.5 nm in our structure. Moreover, a critical Hf layer thickness exists for strong perpendicular magnetic anisotropy on the CoFeB/MgO interface that maintains the properties required for use in MTJs. We also perform X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) to study the effects of film composition, chemical states, and crystallization on the magnetic anisotropy in Hf/FeCoB/MgO/Ta multilayers with Hf layers of various thicknesses.

Original languageEnglish (US)
Pages (from-to)76-81
Number of pages6
JournalJournal of Alloys and Compounds
Volume694
DOIs
StatePublished - 2017

Keywords

  • CoFeB
  • Hf
  • Perpendicular magnetic anisotropy

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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