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<p class="MsoNormal"><span style="font-family:"Georgia","serif"">Please join us for the CME Seminar presented by Cagliyan Kurdak from the University of Michigan on Thursday, May 16<sup>th</sup> at 11:30am in the Smith Seminar Room (1080 PRB).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-family:"Georgia","serif"">“Discovery of a True 3D Topological Insulator: Samarium Hexaboride”<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif"">One of the longest-studied mixed valent insulators, Samarium Hexaboride (SmB6), exhibits a mysterious residual resistivity at low temperatures (T < 4 K), but at a value too high to explain within
the framework of bulk conduction [1]. All efforts over the years to eliminate this resistivity have failed. The recently conjectured existence of a topologically protected surface state in SmB6 [2] could resolve the long-standing mystery surrounding its low-
temperature transport properties.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif"">We developed a novel configuration designed to distinguish bulk-dominated conduction from surface-dominated conduction by exaggerating the geometric differences between the two conduction paths
through contacts placed on both sides of a thin sample. The results of this experiment show that below 3 K, SmB6 has a fully-insulating bulk and an intrinsic metallic surface with a remarkably high conductivity [3]. We argue that the robustness of the surface
conductivity is a signature of the topological protection of the surface states. This discovery resolves the old mystery about the strange transport behavior of this material, and it provides a material in which 2D transport properties of a true topological
state can be studied. I will also present some of our results from transport experiments using a Corbino geometry.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif"">[1] J. W. Allen, B. Batlogg and P. Wachter, Phys. Rev. B 20, 4807 (1979).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif"">[2] M. Dzero, K. Sun, V. Galitski and P. Coleman, Phys. Rev. Lett. 104, 106408 (2010).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif"">[3] S. Wolgast, Ç. Kurdak, K. Sun, J. W. Allen, D. J. Kim and Z. Fisk, arXiv:1211.5104v2.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif"">In collaboration with Steven Wolgast, Yun Suk Eo, Kai Sun, James W.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif"">Allen, Dae-Jong Kim, and Zachary Fisk.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif"">Thank you,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Georgia","serif"">Trisch<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><img width="224" height="45" id="Picture_x0020_1" src="cid:image001.png@01CE5186.64B2A5A0" alt="The Ohio State University"><br>
<b><span style="color:#C00000">Trisch Longbrake</span></b><o:p></o:p></p>
<p class="MsoNormal">Administrative Associate I<br>
<span style="color:#C00000">Department of Physics</span> Condensed Matter<br>
2196 Physics Research Building, 191 W. Woodruff Ave., Columbus, OH 43210<br>
614-292-2778 Office / 614-292-7557 Fax<br>
<a href="mailto:longbrake.6@osu.edu">longbrake.6@osu.edu</a> <a href="http://osu.edu/">
osu.edu</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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