Title: Deciphering the nature of polymorphism and charge density waves in the R2T3X5
(R= Rare earth, T = Transition metal, X = Si, Ge) series
Institut Néel, Room E424 (Salle Louis Weil)
Abstract: At ambient conditions the R2T3X5 (R = Rare earth, T = Transition metal, X = Si, Ge) family crystallizes into six different structure types [1]. Presently, the polymorphs adopting the tetragonal (P4/mnc) Sc2Fe3Si5 and the orthorhombic (Ibam) U2Co3Si5 structure types serve as a platform for exotic physics as they exhibit a plethora of quantum phenomena such as charge density waves (CDW), superconductivity, antiferromagnetism, etc. The two structures are not related by direct group-subgroup relations but rather complex transformations of the basis vectors. On basis of synthesis, incommensurate crystallography and the physics a comparison will be drawn between these two structure types using examples like Sm2Ru3Ge5, Lu2Ir3Si5, Ho2Ir3Si5 and Gd2Os3Si5 [2–5]. Lastly, a phase diagram comprising around 150 compounds as shown in Fig. 1 (see pdf version of this abstract) will be presented to elucidate the origin of CDW in the 2-3-5 family, as compounds falling in this range of 0.526 < c/sqrt(ab) < 0.543 exhibit a CDW and those which are outside the range do not.
[1] W. K. Brown, et al., Handbook on the Physics and Chemistry of Rare Earths, Vol. 64 (Elsevier, 2023) pp. 1–92.
[2] D. E. Bugaris, et al., Journal of the American Chemical Society 139, 4130 (2017).
[3] S. Ramakrishnan, et al., Phys. Rev. B 104, 054116 (2021).
[4] S. Ramakrishnan, et al., Chem. Mater. 35, 1980 (2023).
[5] V. Sharma, et al., Chemistry of Materials 36, 6888 (2024).
