APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011;
Dallas, Texas
Abstract: V7.00004 : Landau-level spectroscopies of a topological insulator
9:48 AM–10:24 AM
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Topological insulators such as Bi$_2$Se$_3$ are characterized by
massless Dirac surface state which would give rise to unique
quantum phenomena in a magnetic field. Although it was
experimentally verified by many ARPES experiments that the
surface electrons are indeed massless, there has been a lack of
studies exploring their quantum properties due to the inevitable
contribution from the bulk electrons in a real material. Using
surface-sensitive STM/STS technique, we selectively probed the
surface massless electrons in Bi$_2$Se$_3$. Under magnetic field
perpendicular to the cleaved surface, a series of Landau levels
(LLs) has been observed in the tunneling spectra. Remarkably,
there is a field-independent LL at the Dirac point, which is a
hallmark of Dirac fermions. We developed a scaling analysis
scheme of LLs based on the Bohr-Sommerfeld quantization
condition which allowed us to determine the energy-momentum
dispersion of the surface state~[1]. Width of the LL peaks in
the spectra becomes smaller near the Fermi energy, which may
suggest that electron-electron correlation plays a role. In
addition to the narrowing of LLs, the spectra near the Fermi
energy exhibit complicated fine structures, which may be
responsible for the anomalous magneto-fingerprint effect~[2].
This work has been done in collaboration with K. Igarashi, M.
Kawamura, H. Takagi and T. Sasagawa.\\[4pt]
[1] T. Hanaguri {\it et al.}, Phys. Rev. B {\bf 82}, 081305(R)
(2010).\\[0pt]
[2] J. G. Checkelsky {\it et al.}, Phys. Rev. Lett. {\bf 103},
246601 (2009).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.V7.4