Ferroic quadrupolar ordering in CeCoSi revealed using ${}^{59}$Co-NMR measurements

Abstract

A nonmagnetic phase transition at $T_0\sim 12$ K in the tetragonal system CeCoSi with a Kramers doublet ground state is reminiscent of an electric quadrupole ordering, even though its well-separated crystal-electric-field (CEF) levels are unlikely to acquire higher-order multipole degrees of freedom. Here, we report ${}^{59}$Co nuclear magnetic resonance (NMR) studies that are highly compatible with a ferroic quadrupole ordering below $T_0$. Changes in the NMR spectra below $T_0$ suggest that an external magnetic field induces ferroic Ce dipole moments orthogonal to the field, enabling domain selection in the nonmagnetic phase. Our findings suggest the presence of a ferroic $O_{zx}$-type quadrupole component in CeCoSi and demonstrate that quadrupole ordering may occur under well-separated CEF levels in tetragonal systems.

7 pages, 6 figures, 1 table

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Cited by in corpus (4)

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• RKKY Interactions and Multipole Order in Ab initio Wannier Model of CeCoSi
• Three-stage Phase Transitions and Field-induced Phases in CeCoSi:A Landau Theory
• Kondo-Peierls transition with nonsymmorphic zone boundary gap formation