Magnetotransport Measurements of the Surface States of Samarium Hexaboride using Corbino Structures

Abstract

The recent conjecture of a topologically-protected surface state in SmB${}_6$ and the verification of robust surface conduction below 4 K have prompted a large effort to understand the 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 SmB${}_6$ 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 $122{\text{ cm}}^2/\text{V}\cdot \text{sec}$ with a carrier density of $2.5\times 10^{13}{\text{ cm}}^{-2}$, which are significantly smaller than indicated by Hall transport studies. This mobility value can explain a 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, 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 anti-localization, but are more likely due to an extrinsic magnetic effect such as the magnetocaloric effect or glassy ordering.

29 pages, 12 figures, PDFLaTeX. This new version is a combination of the prior version and arXiv:1410.7430

References in corpus (11)

• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Surface quantized anomalous Hall current and magneto-electric effect in magnetically disordered topological insulators
• Surface electronic structure of the topological Kondo insulator candidate correlated electron system SmB6
• Correlated Topological Insulators with Mixed Valence
• Direct observation of the spin texture in strongly correlated SmB6 as evidence of the topological Kondo insulator
• Ordering of magnetic impurities and tunable electronic properties of topological insulators
• Hybridization, Inter-Ion Correlation, and Surface States in the Kondo Insulator SmB6
• Tuning bulk and surface conduction in topological Kondo insulator SmB6
• Emergence of a coherent in-gap state in SmB6 Kondo insulator revealed by scanning tunneling spectroscopy
• Correlation between bulk thermodynamic measurements and the low temperature resistance plateau in SmB6
• Electron coherence at low temperatures: The role of magnetic impurities

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• Pressure-resistant intermediate valence in Kondo insulator SmB6
• Bulk and surface electronic properties of SmB6: a hard x-ray photoelectron spectroscopy study
• A highly asymmetric nodal semimetal in bulk SmB6
• Suppression of magnetic excitations near the surface of the topological Kondo insulator SmB6
• Definitive Surface Magnetotransport Study of SmB${}_6$
• Surface-induced positive planar Hall effect in topological Kondo insulator SmB6 microribbons
• Magnetic impurities in Kondo insulators: An application to samarium hexaboride
• Bulk Rotational Symmetry Breaking in Kondo Insulator SmB6
• Diamagnetic Sm${}^{3+}$ in the topological Kondo insulator SmB${}_6$
• Magnetic skyrmion crystal at a topological insulator surface
• Anomalous Hall Effect on the surface of topological Kondo insulators
• A RIXS investigation of the crystal-field splitting of Sm${}^{3+}$ in SmB${}_6$
• Reduction of the low-temperature bulk gap in samarium hexaboride under high magnetic fields
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• Probing the interplay between surface and bulk states in the topological Kondo insulator SmB${}_6$ through conductance fluctuation spectroscopy
• Influence of Helical Spin Structure on the Magnetoresistance of an Ideal Topological Insulator
• An STM perspective on hexaborides: Surface states of the Kondo insulator SmB${}_6$
• Comparative Scanning Tunneling Microscopy Study on Hexaborides
• Unconventional Josephson junctions with topological Kondo insulator weak links
• Phase stability in SmB${}_6$
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• Effects of disorder on the quantum transport properties in topologically nontrivial metal PbTaSe${}_2$
• Correlation Induced Magnetic Topological Phases in Mixed-Valence Compound SmB6
• Persistence of correlation-driven surface states in SmB6 under pressure
• f-electron charge densities probed using core level non-resonant inelastic x-ray scattering