[Supplemental Material]
Abnormal bias dependence of magnetoresistance in CoFeB/MgO/Si spininjection tunnel contacts
June-Young Park1, Seung-heon Chris Baek1,2, Seung-Young Park3, Younghun Jo3, and
Byong-Guk Park1,a)
1
Department of Materials Science and Engineering, KAIST, Daejeon 305-701, Korea
2
Department of Electrical Engineering, KAIST, Daejeon 305-701, Korea
3
Spin Engineering Physics Team, Division of Scientific Instrument, KBSI, Daejeon 305-806, Korea
a) Corresponding Author:
Prof. Byong-Guk Park
Department of Materials Science and Engineering, KAIST
Email: bgpark@kaist.ac.kr
Fax: +82-42-350-3310
1. MR signals at negative bias polarity
Figure S1 shows the magnetoresistance (MR) at negative bias voltages with
perpendicular magnetic field at -0.02mA (a), -0.1mA (b), -1mA (c), and in-plane magnetic
field at -0.1mA (d). At a low bias, such as Fig. S1(a) and Fig. S1(b), the MR signal shows
quite large δ and ε contributions, while the α signal is not shown. However, the existence of
the α signal is appeared after annealing at 200 C. At a high bias condition (Fig. S1(c)), asdeposited sample also shows the α signal, with smaller δ and ε signals. The annealed sample
at high bias shows only α signal. The in-plane MR is decreased after annealing. The overall
tendency of the MR signals for negative bias is the same as those for positive bias conditions,
as mentioned in main article. The slight difference between positive and negative bias, may
be caused by different resistance depending on the bias polarity.
Figure S1. The MR signals of as-deposited (black solid line) and annealed (red dotted line)
samples for negative biases of -0.02 mA (a), -0.1 mA(b), and -1.0 mA (c) with perpendicular
magnetic field and -0.1 mA (d) with in-plane magnetic field. The bias voltages for each
current are -0.036 (-0.054), -0.168 (-0.228), -0.647 (-0.804)V, and -0.168 (-0.228) V,
respectively. [The voltages in the parenthesis are applied voltages to the annealed sample.]
The annealing is done at 200C in a vacuum condition.
2. Tunneling anisotropic magnetoresistnace (TAMR)
The magnitude of the tunneling anisotropic magnetoresistance (TAMR) was obtained
by comparing the resistance of the parallel and perpendicular saturation magnetic field. The
TAMR contributes to the β signal in the Fig. 3 of main article. The magnitude of the TAMR
can be affected by annealing because of its dependence on the defect density in the tunneling
barrier
Figure S2. The tunneling anisotropic magnetoresistance obtained by comparison between
MR curves with perpendicular magnetic field (black solid line) and in-plane magnetic field
(red dotted line) at +0.1mA.
3. Temperature dependent measurement of the I-V characteristics in CoFeB/MgO/Si
tunnel contact
Figure S3 shows the I-V characteristics of the as-deposited sample (a) and annealed
sample (b) are measured between 10K and 300K with an interval of 10K. At temperature
below 100K, the measurements was averaged 15 times at each point to reduce the noise. This
result shows the increase of the resistance with reducing temperature. The resistances at each
bias voltage shown in the Fig. 6(a) of the main text are extracted from these I-V curves. The
temperature dependence of the resistance is stronger at lower bias, and becomes weak with
increasing bias.
Figure S3. The I-V characteristics of (a) as-deposited sample, and (b) annealed sample depending
on the temperatures from 10K ~ 300K (from blue to red) with 10K interval. The inset graph are
magnified for low bias region (-0.1V ~ +0.1V).