{"id":371,"date":"2016-11-18T16:28:35","date_gmt":"2016-11-18T16:28:35","guid":{"rendered":"http:\/\/girsh.rutgers.edu\/?p=371"},"modified":"2018-09-13T19:25:03","modified_gmt":"2018-09-13T19:25:03","slug":"surface-vibrational-modes-of-the-topological-insulator-bi2se3-observed-by-raman-spectroscopy","status":"publish","type":"post","link":"https:\/\/girsh.rutgers.edu\/index.php\/2016\/11\/18\/surface-vibrational-modes-of-the-topological-insulator-bi2se3-observed-by-raman-spectroscopy\/","title":{"rendered":"Surface vibrational modes of the topological insulator Bi2Se3 observed by Raman spectroscopy"},"content":{"rendered":"<p style=\"text-align: left;\"><img fetchpriority=\"high\" decoding=\"async\" class=\"wp-image-341 alignright\" src=\"http:\/\/girsh.rutgers.edu\/wp-content\/uploads\/2016\/11\/Fig3.jpg\" width=\"320\" height=\"727\" \/><br \/>\n<strong>Authors:<\/strong> H.-H. Kung, M. Salehi, I. Boulares, A.F. Kemper, N. Koirala, M. Brahlek, P. Lo\u0014s\u0014t\u0013ak, C. Uher, R. Merlin, X. Wang, S.-W. Cheong, S. Oh, G. Blumberg<\/p>\n<p style=\"text-align: left;\"><strong>Abstract:<\/strong><\/p>\n<div data-canvas-width=\"233.529888\">We present polarization resolved Raman scattering study of surface vibration modes in the topological insulator Bi<sub>2<\/sub>Se<sub>3<\/sub> single crystal and thin films. Besides the 4 Raman active bulk phonons, we observed 4 additional modes with much weaker intensity and slightly lower energy than the bulk counterparts. By symmetry analysis and comparison with theoretical calculation, we assigned these additional modes to out-of-plane surface phonons, where the frequency is slightly modified from the bulk phonon due to out-of-plane lattice distortion near the crystal surface. In particular, two of the surface modes at 60 and 173 cm<sup>-1<\/sup> are associated with Raman active A<sub>1g<\/sub> bulk phonon modes, the other two at 136 and 158 cm<sup>-1<\/sup> are associated with infrared active bulk phonons with A<sub>2u<\/sub> symmetry. The latter become Raman allowed due to restriction of crystalline symmetry from D<sub>3d<\/sub> in the bulk to C<sub>3v<\/sub> at the surface of Bi<sub>2<\/sub>Se<sub>3<\/sub>. The 158 cm<sup>-1<\/sup> surface phonon mode show a Fano line shape, suggesting interaction with an electronic continuum at the crystal surface. In addition, we observed two weak features at 67 and 126 cm<sup>-1<\/sup> likely corresponding to in-plane surface vibrational modes.<\/div>\n<div data-canvas-width=\"233.529888\"><\/div>\n<ul>\n<li><em><a href=\"https:\/\/journals.aps.org\/prb\/abstract\/10.1103\/PhysRevB.95.245406\" target=\"_blank\"><em>Phys. Rev. B<\/em> <strong>95<\/strong>, 245406 (2017)<\/a> (<a href=\"http:\/\/girsh.rutgers.edu\/wp-content\/uploads\/2016\/03\/7.-Kung2017_PhysRevB.95.245406.pdf\" target=\"_blank\">PDF<\/a>)<\/em><\/li>\n<li><em><a href=\"https:\/\/arxiv.org\/abs\/1611.05926\" target=\"_blank\">Read arXiv e-print here<\/a><\/em><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Authors: H.-H. Kung, M. Salehi, I. Boulares, A.F. Kemper, N. Koirala, M. Brahlek, P. Lo\u0014s\u0014t\u0013ak, C. Uher, R. Merlin, X. Wang, S.-W. Cheong, S. Oh, G. Blumberg Abstract: We present polarization resolved Raman scattering study of surface vibration modes in the topological insulator Bi2Se3 single crystal and thin films. Besides the 4 Raman active bulk &hellip;<\/p>\n<p class=\"read-more\"> <a class=\"\" href=\"https:\/\/girsh.rutgers.edu\/index.php\/2016\/11\/18\/surface-vibrational-modes-of-the-topological-insulator-bi2se3-observed-by-raman-spectroscopy\/\"> <span class=\"screen-reader-text\">Surface vibrational modes of the topological insulator Bi2Se3 observed by Raman spectroscopy<\/span> Read More &raquo;<\/a><\/p>\n","protected":false},"author":2,"featured_media":373,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/posts\/371"}],"collection":[{"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/comments?post=371"}],"version-history":[{"count":12,"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/posts\/371\/revisions"}],"predecessor-version":[{"id":795,"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/posts\/371\/revisions\/795"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/media\/373"}],"wp:attachment":[{"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/media?parent=371"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/categories?post=371"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/girsh.rutgers.edu\/index.php\/wp-json\/wp\/v2\/tags?post=371"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}