Evidence for magnon excitation contribution to the magnetoresistance behavior during thermal annealing in CoFeB/MgO/CoFeB magnetic tunnel junctions

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Applied Physics Letters

DOI:https://doi.org/10.1103/PhysRevB.83.224430· OSTI ID:1018247

Ma, Q. L. ^[1]; Wang, Shouguo ^[1]; Wei, H. X. ^[1]; Liu, H. F. ^[1]; Zhang, Xiaoguang ^[2]; Han, Prof. X. F. ^[1]

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1. Institute of Physics, Chinese Academy of Science
2. ORNL

For sputteredCoFeB/MgO/CoFeB magnetic tunnel junctions, it is well known that the tunnelmagnetoresistance (TMR) ratio increases with increasing annealing temperature (Ta) up to a critical value (Tp), and then decreases with further increasing Ta , resulting in a peak around Tp. The improved crystallinity of the MgO barrier and CoFeB electrodes due to annealing has been considered as the main reason for the enhancement of the TMR ratio, especially for Ta < Tp. In this work, the evidence is provided that the magnon excitation plays a great contribution to the magnetoresistance (MR) behavior in annealed samples based on the measurement of dynamic conductance and inelastic electron tunneling (IET) spectra. The magnon activation energy (Ec) obtained from the fits for IET spectra exhibits a similar temperature dependence with that of the TMR ratio. A detailed analysis shows that the magnon excitation, together with improved crystallinity of the MgO barrier and CoFeB layers, is the main contribution to the annealing-temperature-dependent MR behavior.

• Research Organization: Oak Ridge National Laboratory (ORNL); Center for Nanophase Materials Sciences
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1018247
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 22 Vol. 83; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACTIVATION ENERGY
ANNEALING
ELECTRODES
ELECTRONS
EXCITATION
MAGNETORESISTANCE
MAGNONS
SPECTRA
TEMPERATURE DEPENDENCE
TUNNELING