Dependence of exchange bias in NiFe/NiO bilayers on film thickness

• José R. Fermin ^[1]
  1. [1] La Universidad del Zulia

     La Universidad del Zulia

     Venezuela

     
• Localización: Revista Mexicana de Física, ISSN-e 0035-001X, Vol. 63, Nº. 2, 2017, págs. 145-150
• Idioma: inglés
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• Resumen

  • Here we report on the effect of the ferromagnetic (FM) and antiferromagnetic (AF) films thicknesses on the exchange bias field in a FM/AF bilayer. For this, a series of NiFe(t_(NiFe))/NiO(t_(NiO)) bilayers were grown by DC magnetron sputtering onto commercial Si(001) wafers. Magneto-optical hysteresis loops were used as probes to measure the exchange-bias field, and the coercivity field, as functions of the inplane angle, ϕH, and the films’ thicknesses, t_(NiFe) and _(tNiO). The in-plane symmetry of the exchange field and coercivity display unidirectional and uniaxial anisotropies, with angular dependences different from the simple cosϕH and cos^(2)ϕH, respectively. These symmetries are intrinsically sensitive to the thickness of both NiFe and NiO layers. With respect to the FM layer thickness, the exchange bias and coercivity field follow the usual 1/t_(NiFe), while the dependence on the thickness of the AF layer is more complicated, and is characterized by a critical behavior.