Teoman Öztürk

Magnetotransport measurements of the surface states of samarium hexaboride using Corbino structures

Utilizing Corbino disc structures, we have examined the magnetic field response of resistivity for the surface states of SmB6 on different crystalline surfaces at low temperatures. Our results reveal a hysteretic behavior whose magnitude depends on the magnetic field sweep rate and temperature. Although this feature becomes smaller when the field sweep is slower, a complete elimination or saturation is not observed in our slowest sweep-rate measurements, which is much slower than a typical magnetotransport trace. These observations cannot be explained by quantum interference corrections such as weak anti-localization. Instead, they are consistent with behaviors of glassy surface magnetic ordering, whose magnetic origin is most likely from samarium oxide (Sm2O3) forming on the surface during exposure to ambient conditions.The recent conjecture of a topologically protected surface state in

Influence of helical spin structure on the magnetoresistance of an ideal topological insulator

{\mathrm{SmB}}_{6}

The self-consistent calculation of the edge states at quantum Hall effect (QHE) based Mach-Zehnder interferometers (MZI)

and the verification of robust surface conduction below 4 K have prompted a large effort to understand surface states. Conventional Hall transport measurements allow current to flow on all surfaces of a topological insulator, so such measurements are influenced by contributions from multiple surfaces of varying transport character. Instead, we study magnetotransport of

Hysteretic Magnetotransport in SmB6 at Low Magnetic Fields

{\mathrm{SmB}}_{6}

An insight into titania nanopowders modifying with manganese ions: A promising route for highly efficient and stable photoelectrochemical solar cells

using a Corbino geometry, which can directly measure the conductivity of a single, independent surface. Both (011) and (001) crystal surfaces show a strong negative magnetoresistance at all magnetic field angles measured. The (011) surface has a carrier mobility of

The effect of the frozen and pinned surface approximations on the spatial distribution of incompressible and compressible strips in quantum Hall regime

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The self-consistent calculation of the edge states in bilayer quantum Hall bar

with a carrier density of

Kuantum Hall rejiminde bir kuantum Hall çubuğuna uygulanan manyetik alanın ve kapı geriliminin etkisi/ Effects of the magnetic field and gate voltage on a quantum Hall bar in quantum Hall regime

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Calculation of Magnetoresistance of an Ideal Topological Insulator Using Boltzmann Transport

, which are significantly lower than indicated by Hall transport studies. This mobility value can explain the failure so far to observe Shubnikov--de Haas oscillations. Analysis of the angle dependence of conductivity on the (011) surface suggests a combination of a field-dependent enhancement of the carrier density and a suppression of Kondo scattering from native oxide layer magnetic moments as the likely origin of the negative magnetoresistance. Our results also reveal a hysteretic behavior whose magnitude depends on the magnetic field sweep rate and temperature. Although this feature becomes smaller when the field sweep is slower, it does not disappear or saturate during our slowest sweep-rate measurements, which is much slower than a typical magnetotransport trace. These observations cannot be explained by quantum interference corrections such as weak antilocalization but are more likely due to an extrinsic magnetic effect such as the magnetocaloric effect or glassy ordering.

An investigation of the gate dependence in an electronic Aharonov–Bohm interferometer

In an ideal topological insulator, the helical spin structure of surface electrons suppresses backscattering and thus can enhance surface conductivity. We investigate the effect of perpendicular magnetic field on the spin structure of electrons at the Fermi energy and calculate a magnetic-field dependent topological enhancement factor for different disorder potentials, ranging from short-range disorder to screened Coulomb potential. Within the Boltzmann approximation, the topological enhancement factor reaches its maximum value of 4 for a short-range disorder at zero magnetic field and approaches a value of 1 at high magnetic fields independent of the nature of the disorder potential.