## This content will become publicly available on August 15, 2020

## Multiple topological Dirac cones in a mixed-valent Kondo semimetal: $g$ -SmS

## Abstract

We demonstrate theoretically that the golden phase of SmS ($g$ -SmS), a correlated mixed-valent system, exhibits nontrivial surface states with diverse topology. It turns out that this material is an ideal playground to investigate different band topologies in different surface terminations. We have explored surface states on three different (001), (111), and (110) surface terminations. The topological signature on the (001) surface is not apparent due to a hidden Dirac cone inside the bulk-projected bands. In contrast, the (111) surface shows a clear gapless Dirac cone in the gap region, demonstrating the unambiguous topological Kondo nature of $g$-SmS. Most interestingly, the (110) surface exhibits both topological-insulator-type and topological-crystalline-insulator (TCI)-type surface states simultaneously. Two different types of double Dirac cones, Rashba-type and TCI-type, realized on the (001) and (110) surfaces, respectively, are analyzed with the mirror eigenvalues and mirror Chern numbers obtained from the model-independent *ab initio* band calculations.

- Authors:

- Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy
- Pohang Univ. of Science and Technology, Pohang (Korea)
- Catholic Univ. of Korea, Bucheon (Korea)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.

- Publication Date:

- Research Org.:
- Brookhaven National Lab. (BNL), Upton, NY (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

- OSTI Identifier:
- 1566818

- Alternate Identifier(s):
- OSTI ID: 1557388

- Report Number(s):
- BNL-212101-2019-JAAM

Journal ID: ISSN 2475-9953; PRMHAR

- Grant/Contract Number:
- SC0012704; AC02-05CH11231

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Physical Review Materials

- Additional Journal Information:
- Journal Volume: 3; Journal Issue: 8; Journal ID: ISSN 2475-9953

- Publisher:
- American Physical Society (APS)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

### Citation Formats

```
Kang, Chang-Jong, Ryu, Dong-Choon, Kim, Junwon, Kim, Kyoo, Kang, J. -S., Denlinger, J. D., Kotliar, G., and Min, B. I. Multiple topological Dirac cones in a mixed-valent Kondo semimetal: g -SmS. United States: N. p., 2019.
Web. doi:10.1103/PhysRevMaterials.3.081201.
```

```
Kang, Chang-Jong, Ryu, Dong-Choon, Kim, Junwon, Kim, Kyoo, Kang, J. -S., Denlinger, J. D., Kotliar, G., & Min, B. I. Multiple topological Dirac cones in a mixed-valent Kondo semimetal: g -SmS. United States. doi:10.1103/PhysRevMaterials.3.081201.
```

```
Kang, Chang-Jong, Ryu, Dong-Choon, Kim, Junwon, Kim, Kyoo, Kang, J. -S., Denlinger, J. D., Kotliar, G., and Min, B. I. Thu .
"Multiple topological Dirac cones in a mixed-valent Kondo semimetal: g -SmS". United States. doi:10.1103/PhysRevMaterials.3.081201.
```

```
@article{osti_1566818,
```

title = {Multiple topological Dirac cones in a mixed-valent Kondo semimetal: g -SmS},

author = {Kang, Chang-Jong and Ryu, Dong-Choon and Kim, Junwon and Kim, Kyoo and Kang, J. -S. and Denlinger, J. D. and Kotliar, G. and Min, B. I.},

abstractNote = {We demonstrate theoretically that the golden phase of SmS ($g$ -SmS), a correlated mixed-valent system, exhibits nontrivial surface states with diverse topology. It turns out that this material is an ideal playground to investigate different band topologies in different surface terminations. We have explored surface states on three different (001), (111), and (110) surface terminations. The topological signature on the (001) surface is not apparent due to a hidden Dirac cone inside the bulk-projected bands. In contrast, the (111) surface shows a clear gapless Dirac cone in the gap region, demonstrating the unambiguous topological Kondo nature of $g$-SmS. Most interestingly, the (110) surface exhibits both topological-insulator-type and topological-crystalline-insulator (TCI)-type surface states simultaneously. Two different types of double Dirac cones, Rashba-type and TCI-type, realized on the (001) and (110) surfaces, respectively, are analyzed with the mirror eigenvalues and mirror Chern numbers obtained from the model-independent ab initio band calculations.},

doi = {10.1103/PhysRevMaterials.3.081201},

journal = {Physical Review Materials},

number = 8,

volume = 3,

place = {United States},

year = {2019},

month = {8}

}

Works referenced in this record:

##
*Colloquium*: Topological insulators

journal, November 2010

- Hasan, M. Z.; Kane, C. L.
- Reviews of Modern Physics, Vol. 82, Issue 4, p. 3045-3067

##
Topological crystalline insulators in the SnTe material class

journal, January 2012

- Hsieh, Timothy H.; Lin, Hsin; Liu, Junwei
- Nature Communications, Vol. 3, Article No. 982

##
From ultrasoft pseudopotentials to the projector augmented-wave method

journal, January 1999

- Kresse, G.; Joubert, D.
- Physical Review B, Vol. 59, Issue 3, p. 1758-1775

##
Efficient iterative schemes for *ab initio* total-energy calculations using a plane-wave basis set

journal, October 1996

- Kresse, G.; Furthmüller, J.
- Physical Review B, Vol. 54, Issue 16, p. 11169-11186

##
Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set

journal, July 1996

- Kresse, G.; Furthmüller, J.
- Computational Materials Science, Vol. 6, Issue 1, p. 15-50

##
Generalized Gradient Approximation Made Simple

journal, October 1996

- Perdew, John P.; Burke, Kieron; Ernzerhof, Matthias
- Physical Review Letters, Vol. 77, Issue 18, p. 3865-3868