Ordered and tunable Majorana-zero-mode lattice in naturally strained LiFeAs

Geng Li and Hong-Jun Gao
Institute of Physics & University of Chinese Academy of Sciences, CAS, Beijing, China

Majorana zero-modes (MZMs) are spatially-localized zero-energy fractional quasiparticles with non-Abelian braiding statistics. They are believed to hold great promise for topological quantum computing. By using low-temperature and strong-magnetic-field scanning tunneling microscopy/spectroscopy, a breakthrough of Majorana zero mode has been firstly achieved in a single material platform of high-Tc iron-based superconductor, FeTe0.55Se0.45. The mechanism of two distinct classes of vortices presented in this system was revealed, which directly tied with the presence or absence of zero-bias peak. We further found the Majorana conductance plateau in vortices. Both the extrinsic instrumental convoluted broadening and the intrinsic quasiparticle poisoning can reduce the conductance plateau value, and when extrinsic instrumental broadening is removed by deconvolution, the plateau nearly reaches a 2_e_2/h quantized value. Moreover, we confirmed the existence of MZMs in the vortex cores of CaKFe4As4 and LiFeAs. Based on these works mentioned above, most recently, we have successfully achieved the large-scale, highly-ordered and tunable MZM lattice in strained LiFeAs. Notably, more than 90% of the vortices are topological and possess the characteristics of isolated MZMs at the vortex center, forming ordered MZM lattice with the density and the geometry tunable by external magnetic field. With decreasing the spacing of neighboring vortices, the MZMs start to couple with each other. This kind of materials combine the advantages of a simple material, high- Tc, large ratio of Δ/EF and etc. Our results show a great potential of MZMs in the application of topological quantum computations in the future.


References

D. F. Wang and H. -J. Gao et al., Science 362, 333 (2018).
L.Y. Kong and H. -J. Gao et al., Nature Physics 15, 1181 (2019).
S.Y. Zhu and H. -J. Gao et al., Science 367, 189 (2020).
L. Cao, G. Li and H. -J. Gao et al., Nature communications 12, 6312 (2021)
M. Li, G. Li and H. -J. Gao et al., Nature 606, 890 (2022).

**Ordered and tunable Majorana-zero-mode lattice in naturally strained LiFeAs**

Geng Li and Hong-Jun Gao
_Institute of Physics & University of Chinese Academy of Sciences, CAS, Beijing, China_

Majorana zero-modes (MZMs) are spatially-localized zero-energy fractional quasiparticles with non-Abelian braiding statistics. They are believed to hold great promise for topological quantum computing. By using low-temperature and strong-magnetic-field scanning tunneling microscopy/spectroscopy, a breakthrough of Majorana zero mode has been firstly achieved in a single material platform of high-_Tc_ iron-based superconductor, FeTe0.55Se0.45. The mechanism of two distinct classes of vortices presented in this system was revealed, which directly tied with the presence or absence of zero-bias peak. We further found the Majorana conductance plateau in vortices. Both the extrinsic instrumental convoluted broadening and the intrinsic quasiparticle poisoning can reduce the conductance plateau value, and when extrinsic instrumental broadening is removed by deconvolution, the plateau nearly reaches a 2_e_2/_h_ quantized value. Moreover, we confirmed the existence of MZMs in the vortex cores of CaKFe4As4 and LiFeAs. Based on these works mentioned above, most recently, we have successfully achieved the large-scale, highly-ordered and tunable MZM lattice in strained LiFeAs. Notably, more than 90% of the vortices are topological and possess the characteristics of isolated MZMs at the vortex center, forming ordered MZM lattice with the density and the geometry tunable by external magnetic field. With decreasing the spacing of neighboring vortices, the MZMs start to couple with each other. This kind of materials combine the advantages of a simple material, high- _Tc_, large ratio of _Δ_/_EF_ and etc. Our results show a great potential of MZMs in the application of topological quantum computations in the future.


**References**

1. D. F. Wang and H. -J. Gao _et al._, _Science_ **362**, 333 (2018).
2. L.Y. Kong and H. -J. Gao _et al._, _Nature Physics_ **15**, 1181 (2019).
3. S.Y. Zhu and H. -J. Gao _et al_., _Science_ **367**, 189 (2020).
4. L. Cao, G. Li and H. -J. Gao _et al_., _Nature communications_ **12**, 6312 (2021)
5. M. Li, G. Li and H. -J. Gao _et al._, _Nature_ **606**, 890 (2022).

Geng Li

The discovery of topologically non-trivial materials has shaped much of recent research in condensed matter physics.

In particular, the interplay of topology with magnetism and superconductivity has enabled advances that have both fundamental and practical implications. The conference will bring together leading researchers working on these topics and will be broadcast online to allow world-wide participation.