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

Two-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 LiCrTe2, being a 2D-TLA, enriched the range of materials which can present such properties. In this work, muon spin rotation (mu+SR) and neutron powder diffraction (NPD) have been utilized to reveal the true magnetic nature and ground state of LiCrTe2. 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(Cr)=2.36 mu(B). From detailed mu+SR measurements we observe an AFM ordering temperature TN approximate to 125 K. This value is remarkably higher than the one previously reported by magnetic bulk measurements. From mu+SR we are able to extract the magnetic order parameter, whose critical exponent allows us to categorize LiCrTe2 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 LiCrO2.
Funding Agencies|Swedish Foundation for Strategic Research (SSF) within the Swedish national graduate school in neutron scattering (SwedNess); Swedish Research Council VR [2021-06157, 2017-05078]; Carl Tryggers Foundation for Scientific Research [CTS-18:272]; Japan Society for the Promotion Science (JSPS) KAKENHI [JP18H01863, JP20K21149]; Chalmers Area of Advance-Materials Science; JSPS KAKENHI [18KK0150]; Swiss National Science Foundation [PCEFP2-194183]; Swiss National Science Foundation (SNF) [PCEFP2_194183] Funding Source: Swiss National Science Foundation (SNF)