Nuclear and magnetic spin structure of the antiferromagnetic triangular lattice compound LiCrTe2 investigated by $$\mu ^+$$SR, neutron and X-ray diffraction

Abstract

AbstractTwo-dimensional (2D) triangular lattice antiferromagnets (2D-TLA) often manifest intriguing physical and technological properties, due to the strong interplay between lattice geometry and electronic properties. The recently synthesized 2-dimensional transition metal dichalcogenide LiCrTe$$_2$$ 2 , being a 2D-TLA, enriched the range of materials which can present such properties. In this work, muon spin rotation ($$\mu ^+$$ μ + SR) and neutron powder diffraction (NPD) have been utilized to reveal the true magnetic nature and ground state of LiCrTe$$_2$$ 2 . From high-resolution NPD the magnetic spin order at base-temperature is not, as previously suggested, helical, but rather collinear antiferromagnetic (AFM) with ferromagnetic (FM) spin coupling within the ab-plane and AFM coupling along the c-axis. The value if the ordered magnetic Cr moment is established as $$\mu _{\textrm{Cr}}= 2.36~\mu _{\textrm{B}}$$ μ Cr = 2.36 μ B . From detailed $$\mu ^+$$ μ + SR measurements we observe an AFM ordering temperature $$T_{\textrm{N}}\approx 125$$ T N ≈ 125  K. This value is remarkably higher than the one previously reported by magnetic bulk measurements. From $$\mu ^+$$ μ + SR we are able to extract the magnetic order parameter, whose critical exponent allows us to categorize LiCrTe$$_2$$ 2 in the 3D Heisenberg AFM universality class. Finally, by combining our magnetic studies with high-resolution synchrotron X-ray diffraction (XRD), we find a clear coupling between the nuclear and magnetic spin lattices. This suggests the possibility for a strong magnon–phonon coupling, similar to what has been previously observed in the closely related compound LiCrO$$_2$$ 2 .