Transcript Document

The effect of Cr interlayer in epitaxial Fe/MgO/Fe magnetic
tunneling junctions by first principles calculations
J. Zhang, Y. Wang, X.-G. Zhang, X.F. Han
Group M02, State Key Laboratory of Magnetism
Institute of Physics, CAS
Abstract The effect of Cr(001) interlayer in the single crystal Fe(001)/MgO/Cr (x=0–30 ML)/Fe magnetic tunneling junctions
(MTJs) has been investigated by first-principles calculations. The tunneling magnetic resistance (TMR) oscillated with a 2 ML
period as a function of the Cr(001) interlayer thickness. In some thickness range, the TMR oscillated between the positive and
negative values and exhibit interesting odd-even effect.
Two feature of Cr (001):
Fe
MgO
Cr
Fe
Δ1
P
AP
① There is no Δ1
band at the EF of Cr.
The Δ1 electrons
tunneling
at
the
parallel state will be
suppressed
② Layered Antiferromagnetic structure on
Fe (001).
(1)The structure of Fe(001)/MgO(001)/Fe
MTJ with Cr (001) interlayer
(2) The decrease and 2 ML periodic oscillation of TMR (a) and the oscillation of
resistance area (RA) (b) in epitaxial Fe/MgO/Cr/Fe (Ref. 1) MTJ.
(3) Tunneling conductance GP and GAP (a)
and MR ratio (b) of MTJ calculated by
LKKR first principles method.
(4)The transmission distribution in two dimension Brillouin zones for P majority ((a)(e)) and AP ((f)-(g)) with Cr interlayer increasing from 2 to 6 ML
Conclusions Our first principles calculations show that the Cr (001) is a metallic barrier for Δ1 electrons tunneling which causes
the decrease and negative MR. The AFM order of Cr (001) causes the oscillation of P and AP conductance with a period of 2 ML.
This work was supported by MOST, NSFC and CAS.
[1] Rie Matsumoto et al., Phys. Rev. B. 79 (2009) 174436.
[2] F. Greullet et al., Phys. Rev. Lett. 99 (2007) 187202.
[3] J. Zhang,Y. Wang, X.-G. Zhang, X.F. Han, to be submitted.
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