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arXiv · 2104.06119

Crystallographic and magnetic structure of UNi$_4$$^{11}$B

J. Willwater·S. Süllow·M. Reehuis·R. Feyerherm·H. Amitsuka·B. Ouladdiaf·E. Suard·M. Klicpera·M. Vališka·J. Pospíšil·V. Sechovský
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Abstract

We present an extensive powder and single-crystal neutron scattering investigation of the crystallographic structure and magnetic order of the frustrated metallic $f$-electron magnet UNi$_4$B. We carry out a full refinement of the crystallographic structure and conclude that the low-temperature lattice symmetry is orthorhombic (space group Pmm2; cell parameters: $a = 6.963(4)~\r{A}$ , $b = 14.793(9)~\r{A}$ , $c = 17.126(8)~\r{A}$). We determine the magnetically ordered structure, concluding that below $T_\mathrm{N} = 19.5~\mathrm{K}$ the material undergoes a transition into a partially ordered antiferromagnetic state. The magnetic structure is consistent with the existence of toroidal order in this material. We further test the proposal of a second magnetic transition occurring at $330~\mathrm{mK}$, concluding that the thermodynamic anomalies observed at these temperatures do not reflect modifications of the magnetic structure. Our study provides a consistent picture of the interrelationship of structural and magnetic properties in the frustrated magnet UNi$_4$B previously unresolved.

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J. Willwater, S. Süllow, M. Reehuis, R. Feyerherm, H. Amitsuka, B. Ouladdiaf, E. Suard, M. Klicpera, M. Vališka, J. Pospíšil, V. Sechovský. 2021-04-13. Crystallographic and magnetic structure of UNi$_4$$^{11}$B. https://doi.org/10.1103/physrevb.103.184426

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