Transcript 36x48 Vertical Poster

Transport Property of Chromium-Doped
Bismuth Antimony Telluride Nanofilms
Qingyan Fan, Bin Li,，Zhenghua An, Shan Qiao
Institute of Advanced Materials and State Key Laboratory of Surface Physics, Fudan University,
Shanghai 200433, PR China
Localization Property and Ferromagnetism
Abstract
We report results of transport property of mechanically exfoliated single-crystal
Chromium-Doped Bismuth Antimony Telluride nano films . It is found that the
ferromagnetism depend on density of carriers which is different from the results of
ultrathin films grown by molecular beam epitaxy .In addition we investigate the
complex dependence of resistance on temperature, magnetic field to interpret the
relation between carrier-mediated interactions and carriers' localization.
(a) Temperature dependent longitudinal resistance Rxx of the films
Cr0.2Sb1.44Bi0.36Te3 . (b) Magnetic field dependent Hall resistance Rxy of the films at
different temperatures. (c) Magnetoresistance of the films as a perpendicular
magnetic field is applied above the Curie temperature (TC) . (d) Raw data of
magnetoresistance of the films as a perpendicular magnetic field is applied below
the Curie temperature (TC) .
Cr0.2Sb1.44Bi0.36Te3
Results
Sample Preparation
(a)
(b)
3.4
0.2
(b)
80
Rxy/
Rxx/
Tm
3.3
0.0
3.2
-0.2
60
40
(c)
20
0
0.0
-0.2
-500
0
B/oe
500
0
B/oe
Cr0.2Sb1.44Bi0.36Te3
2K
5K
7K
10K
12K
3.3
3.2
3.1
3.0
-40000 -20000
20000 40000
Dependence of Curie temperature (red)
and Tm (blue) on Bi content (x). Error
bars represent temperature spacing in
RAH-T and Rxx-T measurements.
4.0
3.5
0
B/oe
20000 40000
Tm/K
Tc/K
0
25
50
T/K
75
100
Cr0.2Sb(1.8-X)BixTe3
(b)
20
16
Tc/K
16
12
8
3.0
3.00E+025
n(m-3)
1000
20
Curie temperature and Carrier Concentration
2.00E+025
-40000 -20000
4.5
1000
Cr0.2Sb(1.8-X)BixTe3
500
-0.06
-0.08
(a) Magnetic and electric properties of Cr-doped Sb1.8Bi0Te3 films . (b) Magnetic
field dependent Hall resistance Ryx of the Cr0.2Sb1.8Bi0Te3 films at different
temperatures. Temperature dependent longitudinal resistance Rxx of the films
(a)
0
B/oe
(d)
12
4
0.00
0.18
0.36
Bi content(x)
Summary
0.54
We report results of transport property of mechanically exfoliated single-crystal
Chromium-Doped Bismuth Antimony Telluride nano films .The ferromagnetic state
was confirmed by the presence of the anomalous Hall effect. The Curie temperature
is proportional to the density of holes which might suggest that the RKKY interaction
is at play in the bulk state of the sample . The resistance maximum and the
associated negative magnetoresistance near the Curie temperature may be related
to disorder-modified carrier-carrier interactions. These interactions account also for
the low-temperature increase of resistance.
8
1.00E+025
0.00
0.18
0.36
Bi content(x)
0.54
4
0.00
0.18
0.36
Bi content(x)
0.54
Anomalous Hall effect of the Cr0.2Sb(1.8-X)BixTe3 film at T=2K. Dependence of (a)
carrier density and (b) Curie temperature (TC) on Bi content (x). Error bars
represent temperature spacing in RAH-T measurements.
References
[1] Ohno, Making Nonmagnetic Semiconductors Ferromagnetic,
science.281.5379.951
[2] TomaszDietl, Interplay between carrier localization and magnetism in
diluted magnetic and ferromagnetic, J. Phys. Soc. Jpn. 77 (2008).
[3] Liu, Minhao el, Crossover between Weak Antilocalization and Weak
Localization in a Magnetically Doped Topological Insulator.
Phys.Rev.Lett.108.036805
www.postersessi on.com
-0.4
-1000
-500
Cr0.2Sb1.8Bi0Te3
(b)
Rxx/
Rxy/
0.2
-0.04
-1000
40
2.9
Electrical and Magnetic Properties
2K
5K
10K
16K
17K
18K
19K
Rxx(B)
-0.02
(a) SEM image of nanoplates on a 300nm SiO2 substrate. (b) The thicknesses
of a plate in nanometer ,measured by Dektak 150.
30
Cr0.2Sb1.44Bi0.36Te3
12K
15K
17K
19K
25K
30K
60K
0.00
100 120 140 160 180 200
x/um
Cr0.2Sb1.8Bi0Te3
20
T/K
Rxx/
d/nm
10
T/K
(a)
(a)
Cr0.2Sb1.44Bi0.36Te3
2K
7K
10K
12K
13K
www.postersession.com