Collapsed Tetragonal Phase Transition in LaRu$_2$P$_2$

Gil Drachuck; Aashish Sapkota; Wageesha Jayasekara; Karunakar Kothapalli; Sergey L. Bud'ko; Alan I. Goldman; Andreas Kreyssig; Paul C. Canfield

doi:10.1103/PhysRevB.96.184509

paper

Collapsed Tetragonal Phase Transition in LaRu $_{2}$ P $_{2}$

arXiv:1706.04123 · doi:10.1103/PhysRevB.96.184509

Abstract

The structural properties of LaRu $_{2}$ P $_{2}$ under external pressure have been studied up to 14 GPa, employing high-energy x-ray diffraction in a diamond-anvil pressure cell. At ambient conditions, LaRu $_{2}$ P $_{2}$ (I4/mmm) has a tetragonal structure with a bulk modulus of $B = 105 (2)$ GPa and exhibits superconductivity at $T_{c} = 4.1$ K. With the application of pressure, LaRu $_{2}$ P $_{2}$ undergoes a phase transition to a collapsed tetragonal (cT) state with a bulk modulus of $B = 175 (5)$ GPa. At the transition, the c-lattice parameter exhibits a sharp decrease with a concurrent increase of the a-lattice parameter. The cT phase transition in LaRu $_{2}$ P $_{2}$ is consistent with a second order transition, and was found to be temperature dependent, increasing from $P = 3.9 (3)$ GPa at 160 K to $P = 4.6 (3)$ GPa at 300 K. In total, our data are consistent with the cT transition being near, but slightly above 2 GPa at 5 K. Finally, we compare the effect of physical and chemical pressure in the RRu $_{2}$ P $_{2}$ (R = Y, La-Er, Yb) isostructural series of compounds and find them to be analogous.

6 pages, 3 figures

Collapsed Tetragonal Phase Transition in LaRu2​P2​

Abstract

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Collapsed Tetragonal Phase Transition in LaRu $_{2}$ P $_{2}$