[Zurück]

Sami Dzsaber, L. Prochaska, A. Sidorenko, Gaku Eguchi, R. Svagera, M. Waas, A. Prokofiev, Q. Si, S. Paschen:
"Kondo Insulator to Semimetal Transformation Tuned by Spin-Orbit Coupling";
Physical Review Letters, PRL 118 (2017), 246601; S. 1 - 6.

Recent theoretical studies of topologically nontrivial electronic states in Kondo insulators have pointed
to the importance of spin-orbit coupling (SOC) for stabilizing these states. However, systematic
experimental studies that tune the SOC parameter λSOC in Kondo insulators remain elusive. The main
reason is that variations of (chemical) pressure or doping strongly influence the Kondo coupling JK and the
chemical potential μ-both essential parameters determining the ground state of the material-and thus
possible λSOC tuning effects have remained unnoticed. Here, we present the successful growth of the
substitution series Ce3Bi4
ðPt1−xPdxÞ
3 (0 ≤ x ≤ 1) of the archetypal (noncentrosymmetric) Kondo insulator
Ce3Bi4Pt3. The Pt-Pd substitution is isostructural, isoelectronic, and isosize, and it therefore is likely to
leave JK and μ essentially unchanged. By contrast, the large mass difference between the 5d element Pt and
the 4d element Pd leads to a large difference in λSOC, which thus is the dominating tuning parameter in the
series. Surprisingly, with increasing x (decreasing λSOC), we observe a Kondo insulator to semimetal
transition, demonstrating an unprecedented drastic influence of the SOC. The fully substituted end
compound Ce3Bi4Pd3 shows thermodynamic signatures of a recently predicted Weyl-Kondo semimetal.

http://dx.doi.org/10.1103/PhysRevLett.118.246601