# Kondo route to spin inhomogeneities in the honeycomb Kitaev model

## Abstract

Paramagnetic impurities in a quantum spin liquid give rise to Kondo effects with highly unusual properties. We have studied the effect of locally coupling a paramagnetic impurity with the spin-1/2 honeycomb Kitaev model in its gapless spin-liquid phase. The ( impurity) scaling equations are found to be insensitive to the sign of the coupling. The weak and strong coupling fixed points are stable, with the latter corresponding to a noninteracting vacancy and an interacting, spin-1 defect for the antiferromagnetic and ferromagnetic cases, respectively. The ground state in the strong coupling limit in both cases has a nontrivial topology associated with a finite Z(2) flux at the impurity site. For the antiferromagnetic case, this result has been obtained straightforwardly owing to the integrability of the Kitaev model with a vacancy. The strong-coupling limit of the ferromagnetic case is, however, nonintegrable, and we address this problem through exact-diagonalization calculations with finite Kitaev fragments. Our exact diagonalization calculations indicate that the weak-to-strong coupling transition and the topological phase transition occur rather close to each other and are possibly coincident. We also find an intriguing similarity between the magnetic response of the defect and the impurity susceptibility in the two-channel Kondo problem.

- Authors:

- Publication Date:

- Research Org.:
- Argonne National Lab. (ANL), Argonne, IL (United States)

- Sponsoring Org.:
- USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division; Cambridge Commonwealth Trust (CCT)

- OSTI Identifier:
- 1352622

- DOE Contract Number:
- AC02-06CH11357

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physical Review B; Journal Volume: 94; Journal Issue: 2

- Country of Publication:
- United States

- Language:
- English

### Citation Formats

```
Das, S. D., Dhochak, K., and Tripathi, V.
```*Kondo route to spin inhomogeneities in the honeycomb Kitaev model*. United States: N. p., 2016.
Web. doi:10.1103/PhysRevB.94.024411.

```
Das, S. D., Dhochak, K., & Tripathi, V.
```*Kondo route to spin inhomogeneities in the honeycomb Kitaev model*. United States. doi:10.1103/PhysRevB.94.024411.

```
Das, S. D., Dhochak, K., and Tripathi, V. Fri .
"Kondo route to spin inhomogeneities in the honeycomb Kitaev model". United States.
doi:10.1103/PhysRevB.94.024411.
```

```
@article{osti_1352622,
```

title = {Kondo route to spin inhomogeneities in the honeycomb Kitaev model},

author = {Das, S. D. and Dhochak, K. and Tripathi, V.},

abstractNote = {Paramagnetic impurities in a quantum spin liquid give rise to Kondo effects with highly unusual properties. We have studied the effect of locally coupling a paramagnetic impurity with the spin-1/2 honeycomb Kitaev model in its gapless spin-liquid phase. The ( impurity) scaling equations are found to be insensitive to the sign of the coupling. The weak and strong coupling fixed points are stable, with the latter corresponding to a noninteracting vacancy and an interacting, spin-1 defect for the antiferromagnetic and ferromagnetic cases, respectively. The ground state in the strong coupling limit in both cases has a nontrivial topology associated with a finite Z(2) flux at the impurity site. For the antiferromagnetic case, this result has been obtained straightforwardly owing to the integrability of the Kitaev model with a vacancy. The strong-coupling limit of the ferromagnetic case is, however, nonintegrable, and we address this problem through exact-diagonalization calculations with finite Kitaev fragments. Our exact diagonalization calculations indicate that the weak-to-strong coupling transition and the topological phase transition occur rather close to each other and are possibly coincident. We also find an intriguing similarity between the magnetic response of the defect and the impurity susceptibility in the two-channel Kondo problem.},

doi = {10.1103/PhysRevB.94.024411},

journal = {Physical Review B},

number = 2,

volume = 94,

place = {United States},

year = {Fri Jul 01 00:00:00 EDT 2016},

month = {Fri Jul 01 00:00:00 EDT 2016}

}