Dirac versus Weyl fermions in topological insulators: Adler-Bell-Jackiw anomaly in transport phenomena.
Dirac metals (gapless semiconductors) are believed to turn into Weyl metals when perturbations, which break either time reversal symmetry or inversion symmetry, are employed. However, no experimental evidence has been reported for the existence of Weyl fermions in three dimensions. Applying magnetic fields near the topological phase transition from a topological insulator to a band insulator in Bi1-xSbx we observe not only the weak antilocalization phenomenon in magnetoconductivity near zero magnetic fields (B<0.4  T), but also its upturn above 0.4 T only for E//B. This "incompatible" coexistence between weak antilocalization and "negative" magnetoresistivity is attributed to the Adler-Bell-Jackiw anomaly ("topological" E·B term) in the presence of weak antilocalization corrections.
Department of Physics, College of Natural Science, Daegu University, Gyeongbuk 712-714, Korea.
Heon-Jung
HJ
Kim
Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Korea and Institute of Edge of Theoretical Science (IES), Hogil Kim Memorial Building, 5th floor, POSTECH, Pohang, Gyeongbuk 790-784, Korea.
Ki-Seok
KS
Kim
Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China.
J-F
JF
Wang
Department of Physics, Faculty of Science, Yamagata University, Kojirakawa, Yamagata 990-8560, Japan.
M
M
Sasaki
Department of Electronics and Computer Science, Iwaki Meisei University, Iwaki, Fukushima 970-8551, Japan.
N
N
Satoh
Department of Physics, Faculty of Science, Yamagata University, Kojirakawa, Yamagata 990-8560, Japan.
A
A
Ohnishi
Department of Physics, Faculty of Science, Yamagata University, Kojirakawa, Yamagata 990-8560, Japan.
M
M
Kitaura
Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China.
M
M
Yang
Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China.
L
L
Li