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Angle-resolved photoemission spectroscopy study on the surface states of the correlated topological insulator YbB6.

Xia M, Jiang J, Ye ZR, Wang YH, Zhang Y, Chen SD, Niu XH, Xu DF, Chen F, Chen XH, Xie BP, Zhang T, Feng DL - Sci Rep (2014)

Bottom Line: Circular dichroism photoemission spectra suggest that these in-gap states possess chirality of orbital angular momentum, which is related to the chiral spin texture, further indicative of their topological nature.The observed insulating gap of YbB6 is about 100 meV, larger than that found by theoretical calculations.Our results present strong evidence that YbB6 is a correlated topological insulator and provide a foundation for further studies of this promising material.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China [2].

ABSTRACT
YbB6 is recently predicted to be a moderately correlated topological insulator, which provides a playground to explore the interplay between correlation and topological properties. With angle-resolved photoemission spectroscopy, we directly observed almost linearly dispersive bands around the time-reversal invariant momenta and with negligible kz dependence, consistent with odd number of surface states crossing the Fermi level in a Z2 topological insulator. Circular dichroism photoemission spectra suggest that these in-gap states possess chirality of orbital angular momentum, which is related to the chiral spin texture, further indicative of their topological nature. The observed insulating gap of YbB6 is about 100 meV, larger than that found by theoretical calculations. Our results present strong evidence that YbB6 is a correlated topological insulator and provide a foundation for further studies of this promising material.

No MeSH data available.


Related in: MedlinePlus

Crystal structure and Sample characterization.(a) Crystal structure of YbB6. (b) Bulk and surface Brillouin zone of YbB6 and the high symmetry points. (c) X-ray diffraction pattern of YbB6 single crystals. (d) Resistivity of YbB6 single crystals measured from 2 K to 300 K.
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f1: Crystal structure and Sample characterization.(a) Crystal structure of YbB6. (b) Bulk and surface Brillouin zone of YbB6 and the high symmetry points. (c) X-ray diffraction pattern of YbB6 single crystals. (d) Resistivity of YbB6 single crystals measured from 2 K to 300 K.

Mentions: Sample preparation and experimental details are described in the Methods section. YbB6 crystallizes in the cubic Pm-3m space group and can be considered as the CsCl-type structure with the Yb ions and the B6 octahedra being located at the corner and the body center of the cubic lattice, respectively, as shown in Fig. 1(a). Figure 1(b) shows the bulk BZ together with the projected surface BZ. The high symmetry points we used are indicated in this panel. The X-ray diffraction pattern presented in Fig. 1(c) indicates a high sample quality of our single crystal and the natural surface is the (001) surface. The resistivity of YbB6 single crystal shows a metallic behavior down to 2 K (Fig. 1(d)), consistent with previous report in ref. 23, which can be further understood by the coexistence of the bulk band with the surface states that will be discussed below.


Angle-resolved photoemission spectroscopy study on the surface states of the correlated topological insulator YbB6.

Xia M, Jiang J, Ye ZR, Wang YH, Zhang Y, Chen SD, Niu XH, Xu DF, Chen F, Chen XH, Xie BP, Zhang T, Feng DL - Sci Rep (2014)

Crystal structure and Sample characterization.(a) Crystal structure of YbB6. (b) Bulk and surface Brillouin zone of YbB6 and the high symmetry points. (c) X-ray diffraction pattern of YbB6 single crystals. (d) Resistivity of YbB6 single crystals measured from 2 K to 300 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126005&req=5

f1: Crystal structure and Sample characterization.(a) Crystal structure of YbB6. (b) Bulk and surface Brillouin zone of YbB6 and the high symmetry points. (c) X-ray diffraction pattern of YbB6 single crystals. (d) Resistivity of YbB6 single crystals measured from 2 K to 300 K.
Mentions: Sample preparation and experimental details are described in the Methods section. YbB6 crystallizes in the cubic Pm-3m space group and can be considered as the CsCl-type structure with the Yb ions and the B6 octahedra being located at the corner and the body center of the cubic lattice, respectively, as shown in Fig. 1(a). Figure 1(b) shows the bulk BZ together with the projected surface BZ. The high symmetry points we used are indicated in this panel. The X-ray diffraction pattern presented in Fig. 1(c) indicates a high sample quality of our single crystal and the natural surface is the (001) surface. The resistivity of YbB6 single crystal shows a metallic behavior down to 2 K (Fig. 1(d)), consistent with previous report in ref. 23, which can be further understood by the coexistence of the bulk band with the surface states that will be discussed below.

Bottom Line: Circular dichroism photoemission spectra suggest that these in-gap states possess chirality of orbital angular momentum, which is related to the chiral spin texture, further indicative of their topological nature.The observed insulating gap of YbB6 is about 100 meV, larger than that found by theoretical calculations.Our results present strong evidence that YbB6 is a correlated topological insulator and provide a foundation for further studies of this promising material.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China [2].

ABSTRACT
YbB6 is recently predicted to be a moderately correlated topological insulator, which provides a playground to explore the interplay between correlation and topological properties. With angle-resolved photoemission spectroscopy, we directly observed almost linearly dispersive bands around the time-reversal invariant momenta and with negligible kz dependence, consistent with odd number of surface states crossing the Fermi level in a Z2 topological insulator. Circular dichroism photoemission spectra suggest that these in-gap states possess chirality of orbital angular momentum, which is related to the chiral spin texture, further indicative of their topological nature. The observed insulating gap of YbB6 is about 100 meV, larger than that found by theoretical calculations. Our results present strong evidence that YbB6 is a correlated topological insulator and provide a foundation for further studies of this promising material.

No MeSH data available.


Related in: MedlinePlus