Effect of annealing on the temperature dependence of inelastic tunneling contributions vis-à-vis tunneling magnetoresistance and barrier parameters in CoFe/MgO/NiFe magnetic tunnel junctions

Journal Article · Fri Feb 28 04:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4866078· OSTI ID:22278016

Bhusan Singh, Braj; Chaudhary, Sujeet ^[1]

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1. Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi-110 016 (India)

The effect of annealing on the changes in the inelastic tunneling contributions in tunneling conductance of ion beam sputtered CoFe/MgO/NiFe magnetic tunnel junctions (MTJs) is investigated. The inelastic contributions are evaluated using hopping conduction model of Glazman and Matveev in the temperature range of 25–300 K. The hopping through number of series of localized states present in the barrier due to structural defects increases from 9 (in as deposited MTJ) to 18 after annealing (at 200 °C/1 h); although no changes in the interface roughness of CoFe-MgO and MgO-NiFe interfaces are observed as revealed by the x-ray reflectance studies on planar MTJs. The bias dependence of tunneling magnetoresistance (TMR) at 25 K is found to get improved after annealing as revealed by the value V{sub 1/2} (the bias value at which the TMR reaches to half of its value at nearly zero bias); which is 78 mV (in MTJ annealed at 200 °C/1 h) 2.5 times the value of 33 mV (in as deposited MTJ). At 25 K the inelastic tunneling spectra revealed the presence of zero bias anomaly and magnon excitations in the range of 10–15 mV. While the barrier height exhibited a strong temperature dependence with nearly 100% increase from the value at 300 K to 25 K, the temperature dependence of TMR becomes steep after annealing.

• OSTI ID: 22278016
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 115; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
COBALT
EXCITATION
INTERFACES
INTERMETALLIC COMPOUNDS
IRON
MAGNESIUM OXIDES
MAGNETORESISTANCE
NICKEL
ROUGHNESS
TEMPERATURE DEPENDENCE
TUNNEL EFFECT
X RADIATION