Multipolar magnetism in $5d^2$ vacancy-ordered halide double perovskites
Abstract: Vacancy-ordered halide double perovskites hosting 4d/5d transition metals have emerged as a distinct platform for investigating unconventional magnetism arising out of the interplay of strong atomic spin-orbit coupling (SOC) and Coulomb interactions. Focusing on the $d2$ system Cs$_2$WCl$_6$, our ab initio electronic structure calculation reveals very narrow electronic bands, fulfilling the necessary condition to realize exotic orders. Using this input, we solve the many-body spin-orbit coupled single-site problem by exact diagonalization and show that the multiplet structure of Cs$_2$WCl$_6$ hosts ground non-Kramers doublets on W, with vanishing dipole moment and a small gap to an excited magnetic triplet. Our work provides the rationale for the observed strong deviation from the classic Kotani behaviour in Cs$_2$WCl$_6$ for the measured temperature dependence of the magnetic moment. The non-Kramers doublets on W exhibit non-zero quadrupolar and octupolar moments, and our calculated two-site exchange supports the dominance of inter-site octupolar exchange over quadrupolar interactions. We predict ferro-octupolar order with a transition temperature $T_c \sim 5$K which may get somewhat suppressed by quantum fluctuations and disorder; this could be tested in future low-temperature experiments.
- M. B. Salamon and M. Jaime, The physics of manganites: Structure and transport, Rev. Mod. Phys. 73, 583 (2001).
- J. M. D. Coey, M. Viret and S. von Molnár, Mixed-valence manganites, Advances in Physics 48, 167 (1999).
- M. A. Pena and J. L. G. Fierro, Chemical structures and performance of perovskite oxides, Chemical Reviews 101, 1981 (2001).
- C. N. R. Rao, A. K. Cheetham, and R. Mahesh, Giant magnetoresistance and related properties of rare-earth manganates and other oxide systems, Chemistry of Materials 8, 2421 (1996).
- S. Vasala and M. Karppinen, A22{}_{2}start_FLOATSUBSCRIPT 2 end_FLOATSUBSCRIPTB′′{}^{\prime}start_FLOATSUPERSCRIPT ′ end_FLOATSUPERSCRIPTB′′′′{}^{\prime\prime}start_FLOATSUPERSCRIPT ′ ′ end_FLOATSUPERSCRIPTO66{}_{6}start_FLOATSUBSCRIPT 6 end_FLOATSUBSCRIPT perovskites: A review, Progress in Solid State Chemistry 43, 1 (2015).
- T. Saha-Dasgupta, Double perovskites with 3d and 4d/5d transition metals: compounds with promises, Materials Research Express 7, 014003 (2020).
- G. Khaliullin, Excitonic magnetism in van Vleck–type d4superscript𝑑4{d}^{4}italic_d start_POSTSUPERSCRIPT 4 end_POSTSUPERSCRIPT Mott insulators, Phys. Rev. Lett. 111, 197201 (2013).
- D. Hirai and Z. Hiroi, Successive symmetry breaking in a jeffeff{}_{\rm eff}start_FLOATSUBSCRIPT roman_eff end_FLOATSUBSCRIPT = 3/2 quartet in the spin-orbit coupled insulator Ba22{}_{2}start_FLOATSUBSCRIPT 2 end_FLOATSUBSCRIPTMgReO66{}_{6}start_FLOATSUBSCRIPT 6 end_FLOATSUBSCRIPT, J. Phys. Soc. Jpn. 88, 064712 (2019).
- D. F. Mosca, C. Franchini, and L. V. Pourovskii, Interplay of superexchange and vibronic effects in the hidden order of Ba22{}_{2}start_FLOATSUBSCRIPT 2 end_FLOATSUBSCRIPTMgReO66{}_{6}start_FLOATSUBSCRIPT 6 end_FLOATSUBSCRIPT unravelled from first principles (2024), arXiv:2402.15564 [cond-mat.str-el] .
- A. Paramekanti, D. D. Maharaj, and B. D. Gaulin, Octupolar order in d𝑑ditalic_d-orbital Mott insulators, Phys. Rev. B 101, 054439 (2020).
- S. Voleti, A. Haldar, and A. Paramekanti, Octupolar order and Ising quantum criticality tuned by strain and dimensionality: Application to d𝑑ditalic_d-orbital Mott insulators, Phys. Rev. B 104, 174431 (2021).
- A. E. Fedorovskiy, N. A. Drigo, and M. K. Nazeeruddin, The role of Goldschmidt’s tolerance factor in the formation of A22{}_{2}start_FLOATSUBSCRIPT 2 end_FLOATSUBSCRIPTBX66{}_{6}start_FLOATSUBSCRIPT 6 end_FLOATSUBSCRIPT double halide perovskites and its optimal range, Small Methods 4, 1900426 (2020).
- C. D. Kennedy and R. D. Peacock, 629. complex chlorides and bromides of quadrivalent tungsten, J. Chem. Soc. , 3392 (1963).
- M. Kotani, On the magnetic moment of complex ions. (i), Journal of the Physical Society of Japan 4, 293 (1949).
- H. Das, M. De Raychaudhury, and T. Saha-Dasgupta, Moderate to large magneto-optical signals in high Tc double perovskites, Applied Physics Letters 92, 201912 (2008).
- O. K. Andersen and T. Saha-Dasgupta, Muffin-tin orbitals of arbitrary order, Phys. Rev. B 62, R16219 (2000).
- A. Georges, L. d. Medici, and J. Mravlje, Strong correlations from Hund’s coupling, Annual Review of Condensed Matter Physics 4, 137 (2013).
- K. W. H. Stevens, Matrix elements and operator equivalents connected with the magnetic properties of rare earth ions, Proceedings of the Physical Society. Section A 65, 209 (1952).
- J. H. Van Vleck, On dielectric constants and magnetic susceptibilities in the new quantum mechanics part iii—application to dia- and paramagnetism, Phys. Rev. 31, 587 (1928).
- D. Churchill and H.-Y. Kee, Competing multipolar orders in a face-centered cubic lattice: Application to the osmium double perovskites, Phys. Rev. B 105, 014438 (2022).
- G. Kresse and D. Joubert, From ultrasoft pseudopotentials to the projector augmented-wave method, Phys. Rev. B 59, 1758 (1999).
- G. Kresse and J. Hafner, Ab initio molecular dynamics for liquid metals, Phys. Rev. B 47, 558 (1993).
- J. P. Perdew, K. Burke, and M. Ernzerhof, Generalized gradient approximation made simple, Phys. Rev. Lett. 77, 3865 (1996).
- O. K. Andersen, Linear methods in band theory, Phys. Rev. B 12, 3060 (1975).
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