title: Emergent photovoltage on SmB6 surface upon bulk-gap evolution revealed by pump-and-probe photoemission spectroscopy.
abstract: Recent studies suggest that an exemplary Kondo insulator SmB6 belongs to a new class of topological insulators (TIs), in which non-trivial spin-polarized metallic states emerge on surface upon the formation of Kondo hybridization gap in the bulk. Remarkably, the bulk resistivity reaches more than 20 Ω cm at 4 K, making SmB6 a candidate for a so-called bulk-insulating TI. We here investigate optical-pulse responses of SmB6 by pump-and-probe photoemission spectroscopy. Surface photovoltage effect is observed below ~90 K. This indicates that an optically-active band bending region develops beneath the novel metallic surface upon the bulk-gap evolution. The photovoltaic effect persists for >200 µs, which is long enough to be detected by electronics devices, and could be utilized for optical gating of the novel metallic surface.
authors: ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
authors: Y
authors: Y
authors: Ishida
authors: ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
authors: T
authors: T
authors: Otsu
authors: ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
authors: T
authors: T
authors: Shimada
authors: ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
authors: M
authors: M
authors: Okawa
authors: ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
authors: Y
authors: Y
authors: Kobayashi
authors: 1] College of Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan [2] Department of Quantum Matter and Institute for Advanced Materials Research, Hiroshima University, Higashi-hiroshima, Hiroshima 739-8530, Japan.
authors: F
authors: F
authors: Iga
authors: T
authors: T
authors: Takabatake
authors: Department of Quantum Matter and Institute for Advanced Materials Research, Hiroshima University, Higashi-hiroshima, Hiroshima 739-8530, Japan.
authors: Y
authors: Y
authors: Takabatake
authors: ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
authors: S
authors: S
authors: Shin
references: Nat Commun. 2014;5:4566
references: 25074332
references: Proc Natl Acad Sci U S A. 2014 Apr 1;111(13):4798-802
references: 24639519
references: Phys Rev Lett. 1987 Sep 28;59(13):1460-1463
references: 10035240
references: Rev Sci Instrum. 2014 Dec;85(12):123904
references: 25554306
references: Phys Rev Lett. 2010 Mar 12;104(10):106408
references: 20366446
references: Phys Rev Lett. 1989 Feb 13;62(7):815-818
references: 10040340
references: Phys Rev Lett. 1990 Apr 30;64(18):2172-2175
references: 10041602
references: Phys Rev Lett. 2014 Jul 11;113(2):026801
references: 25062217
references: Nat Commun. 2013;4:3010
references: 24346657
references: Sci Rep. 2011;1:64
references: 22355583
references: Phys Rev Lett. 2007 Nov 9;99(19):197001
references: 18233106
references: Nat Commun. 2013;4:2991
references: 24346502
references: Sci Rep. 2013 Nov 06;3:3150
references: 24193196
references: Phys Rev B Condens Matter. 1992 Nov 15;46(20):13592-13595
references: 10003408
references: Phys Rev Lett. 2003 Dec 31;91(26 Pt 1):267002
references: 14754080
references: Nat Commun. 2014;5:3003
references: 24389793
references: Phys Rev Lett. 2011 Jul 1;107(1):016801
references: 21797561
references: Phys Rev Lett. 2013 Nov 22;111(21):216402
references: 24313508
references: Phys Rev Lett. 1995 Feb 27;74(9):1629-1632
references: 10059077
references: Nat Mater. 2014 May;13(5):466-70
references: 24658115
references: Phys Rev Lett. 2012 Jan 6;108(1):016402
references: 22304274
references: Phys Rev Lett. 2010 Apr 30;104(17):176403
references: 20482121
references: Phys Rev Lett. 2000 Jul 31;85(5):1048-51
references: 10991471