Universität zu Köln

Borgwardt, N., Lux, J., Vergara, I., Wang, Zhiwei ORCID: 0000-0003-0182-2471, Taskin, A. A., Segawa, Kouji, van Loosdrecht, P. H. M., Ando, Yoichi ORCID: 0000-0002-3553-3355, Rosch, A. and Grueninger, M. (2016). Self-organized charge puddles in a three-dimensional topological material. Phys. Rev. B, 93 (24). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2469-9969

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Abstract

In three-dimensional (3D) topological materials, tuning of the bulk chemical potential is of crucial importance for observing their topological properties; for example, Weyl semimetals require chemical-potential tuning to the bulk Weyl nodes, while 3D topological insulators require tuning into the bulk band gap. Such tuning is often realized by compensation, i.e., by balancing the density of acceptors and donors. Here we show that in such a compensated 3D topological material, the possibility of local chemical-potential tuning is limited by the formation of self-organized charge puddles. The puddles arise from large fluctuations of the Coulomb potential of donors and acceptors. Their emergence is akin to the case of graphene, where charge puddles are already established as a key paradigm. However, there is an important difference: Puddles in graphene are simply dictated by the static distribution of defects in the substrate, whereas we find that puddles in 3D systems self-organize in a nontrivial way and show a strong temperature dependence. Such a self-organization is revealed by measurements of the optical conductivity of the bulk-insulating 3D topological insulator BiSbTeSe2, which pinpoints the presence of puddles at low temperatures as well as their surprising evaporation on a temperature scale of 30-40 K. The experimental observation is described semiquantitatively by Monte Carlo simulations. These show that the temperature scale is set by the Coulomb interaction between neighboring dopants and that puddles are destroyed by thermally activated carriers in a highly nonlinear screening process. This result indicates that understanding charge puddles is crucial for the control of the chemical potential in compensated 3D topological materials.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Borgwardt, N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lux, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Vergara, I. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wang, Zhiwei UNSPECIFIED orcid.org/0000-0003-0182-2471 UNSPECIFIED Taskin, A. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Segawa, Kouji UNSPECIFIED UNSPECIFIED UNSPECIFIED van Loosdrecht, P. H. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ando, Yoichi UNSPECIFIED orcid.org/0000-0002-3553-3355 UNSPECIFIED Rosch, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Grueninger, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-272050
DOI:	10.1103/PhysRevB.93.245149
Journal or Publication Title:	Phys. Rev. B
Volume:	93
Number:	24
Date:	2016
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	2469-9969
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute of Physics II
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language WEYL FERMION SEMIMETAL; CRYSTALLINE INSULATOR; QUANTUM OSCILLATIONS; OPTICAL PROPERTIES; PHASE-TRANSITION; DIRAC SEMIMETAL; SURFACE-STATE; DISCOVERY; ARCS; CONDUCTIVITY Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/27205