Thermodynamic prediction on the formation of oxides in MgO-based magnetic tunnel junctions

Jong Ho Jung, Sang Ho Lim

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The equilibrium oxygen partial pressures for various oxides, which can be formed in CoFeB/MgO/CoFeB junctions, are calculated over a wide temperature range of 298 K ∼ 1000 K by using available data for the temperature dependences of the heat capacities of the constituent elements. The equilibrium oxygen partial pressure is lowest in MgO over the entire temperature range, indicating that MgO is the most stable oxide among the various oxides. The next most stable oxide is B2O3, followed by Fe oxides (FeO, Fe3O4 and Fe2O3) and Co oxides (CoO and Co3O4). The same order of stability is predicted from the results for the standard free energy of formation per mol of oxygen and from those for the standard enthalpy of formation per mol of oxygen, except for the Fe oxides. The relative stability among the Fe oxides is incorrectly predicted from the standard enthalpy of formation per mol of oxygen, indicating the need for great care in using this thermodynamic parameter for the prediction of phase stability. The standard free energy of formation and the standard enthalpy of formation per mol of oxides, which were used frequently in the past, are shown not to be suitable for the prediction of oxide formation.

Original languageEnglish
Pages (from-to)2664-2669
Number of pages6
JournalJournal of the Korean Physical Society
Volume53
Issue number5 PART 1
Publication statusPublished - 2008 Nov 1

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tunnel junctions
thermodynamics
oxides
predictions
oxygen
enthalpy
energy of formation
partial pressure
free energy
specific heat
temperature dependence
temperature

Keywords

  • CoFeB electrode
  • MgO barrier
  • Oxide formation
  • Oxides in magnetic tunnel junctions
  • Thermodynamic prediction

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Thermodynamic prediction on the formation of oxides in MgO-based magnetic tunnel junctions. / Jung, Jong Ho; Lim, Sang Ho.

In: Journal of the Korean Physical Society, Vol. 53, No. 5 PART 1, 01.11.2008, p. 2664-2669.

Research output: Contribution to journalArticle

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AB - The equilibrium oxygen partial pressures for various oxides, which can be formed in CoFeB/MgO/CoFeB junctions, are calculated over a wide temperature range of 298 K ∼ 1000 K by using available data for the temperature dependences of the heat capacities of the constituent elements. The equilibrium oxygen partial pressure is lowest in MgO over the entire temperature range, indicating that MgO is the most stable oxide among the various oxides. The next most stable oxide is B2O3, followed by Fe oxides (FeO, Fe3O4 and Fe2O3) and Co oxides (CoO and Co3O4). The same order of stability is predicted from the results for the standard free energy of formation per mol of oxygen and from those for the standard enthalpy of formation per mol of oxygen, except for the Fe oxides. The relative stability among the Fe oxides is incorrectly predicted from the standard enthalpy of formation per mol of oxygen, indicating the need for great care in using this thermodynamic parameter for the prediction of phase stability. The standard free energy of formation and the standard enthalpy of formation per mol of oxides, which were used frequently in the past, are shown not to be suitable for the prediction of oxide formation.

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