Magneto-elastic coupling across the first-order transition in the distorted kagome lattice antiferromagnet Dy3Ru4Al12

• Dy3Ru4Al12 displays a first-order phase transition at the Néel temperature, 7 K.
• No structural phase transition has been found between 2.5 and 300 K.
• However, the compound undergoes a small orthorhombic distortion of ~2×10−5 at 7 K.
• We propose that the first-order transition is driven by exchange interactions.

Structural changes through the first-order paramagnetic–antiferromagnetic phase transition of Dy3Ru4Al12 at 7 K have been studied by means of X-ray diffraction and thermal expansion measurements. The compound crystallizes in a hexagonal crystal structure of Gd3Ru4Al12 type (P63/mmc space group), and no structural phase transition has been found in the temperature interval between 2.5 and 300 K. Nevertheless, due to the spin-lattice coupling the crystal volume undergoes a small orthorhombic distortion of the order of 2×10−5 as the compound enters the antiferromagnetic state. We propose that the first-order phase transition is not driven by the structural changes but rather by the exchange interactions present in the system.