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arXiv · 1705.08876

Realization of the Axial Next-Nearest-Neighbor Ising model in U$_3$Al$_2$Ge$_3$

David M Fobes·Shi-Zeng Lin·Nirmal J Ghimire·Eric D Bauer·Joe D Thompson·Markus Bleuel·Lisa M DeBeer-Schmitt·Marc Janoschek
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Abstract

Here we report small-angle neutron scattering (SANS) measurements and theoretical modeling of U$_3$Al$_2$Ge$_3$. Analysis of the SANS data reveals a phase transition to sinusoidally modulated magnetic order, at $T_{\mathrm{N}}=63$~K to be second order, and a first order phase transition to ferromagnetic order at $T_{\mathrm{c}}=48$~K. Within the sinusoidally modulated magnetic phase ($T_{\mathrm{c}} < T < T_{\mathrm{N}}$), we uncover a dramatic change, by a factor of three, in the ordering wave-vector as a function of temperature. These observations all indicate that U$_3$Al$_2$Ge$_3$ is a close realization of the three-dimensional Axial Next-Nearest-Neighbor Ising model, a prototypical framework for describing commensurate to incommensurate phase transitions in frustrated magnets.

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David M Fobes, Shi-Zeng Lin, Nirmal J Ghimire, Eric D Bauer, Joe D Thompson, Markus Bleuel, Lisa M DeBeer-Schmitt, Marc Janoschek. 2017-11-09. Realization of the Axial Next-Nearest-Neighbor Ising model in U$_3$Al$_2$Ge$_3$. https://doi.org/10.1103/physrevb.96.174413

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