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arXiv · 1809.07317

Structural distortion and incommensurate noncollinear magnetism in EuAg4As2

Bing Shen·Chaowei Hu·Huibo Cao·Xin Gui·Eve Emmanouilidou·Weiwei Xie·Ni Ni
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Abstract

Layered pnictide materials have provided a fruitful platform to study various emergent phenomena, including superconductivity, magnetism, charge density waves, etc. Here we report the observation of structural distortion and noncollinear magnetism in layered pnictide EuAg$_4$As$_2$ via transport, magnetization, single crystal X-ray and neutron diffraction data. EuAg$_4$As$_2$ single crystal shows a structural distortion at 120 K, where two sets of superlattice peaks with the propagation vectors of $q_1=\pm$(0, 0.25, 0.5) and $q_2=\pm$(0.25, 0, 1) emerge. Between 9 K to 15 K, the hexagonal Eu$^{2+}$ sub-lattice enters an unpinned state, with magnetic Bragg reflections pictured as circular-sectors. Below 9 K, it orders in an incommensurate noncollinear antiferromagnetic state with a well-defined propagation wavevector of (0, 0.1, 0.12), where the magnetic structure is helical along the $c$ axis and cycloidal along the $b$ axis with a moment of 6.4 $\mu_B$/Eu$^{2+}$. Furthermore, rich magnetic phases under magnetic fields, large magnetoresistance, and strong coupling between charge carriers and magnetism in EuAg$_4$As$_2$ are revealed.

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Bing Shen, Chaowei Hu, Huibo Cao, Xin Gui, Eve Emmanouilidou, Weiwei Xie, Ni Ni. 2018-09-19. Structural distortion and incommensurate noncollinear magnetism in EuAg4As2. https://doi.org/10.1103/physrevmaterials.4.064419

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