Evidence of an improper displacive phase transition in Cd${}_2$Re${}_2$O${}_7$ via time-resolved coherent phonon spectroscopy

Abstract

We have used a combination of ultrafast coherent phonon spectroscopy, ultrafast thermometry, and time-dependent Landau theory to study the inversion symmetry breaking phase transition at $T_c=200$ K in the strongly spin-orbit coupled correlated metal Cd${}_2$Re${}_2$O${}_7$. We establish that the structural distortion at $T_c$ is a secondary effect through the absence of any softening of its associated phonon mode, which supports a purely electronically driven mechanism. However, the phonon lifetime exhibits an anomalously strong temperature dependence that decreases linearly to zero near $T_c$. We show that this behavior naturally explains the spurious appearance of phonon softening in previous Raman spectroscopy experiments and should be a prevalent feature of correlated electron systems with linearly coupled order parameters.

5 pages main text, 5 figures, 7 pages supplementary information

References in corpus (7)

• Experimental demonstration of hybrid improper ferroelectricity and presence of abundant charged walls in (Ca,Sr)${}_3$Ti${}_2$O${}_7$ crystals
• Fermi liquid instabilities in the spin channel
• Parity-breaking phases of spin-orbit-coupled metals with gyrotropic, ferroelectric and multipolar orders
• Dynamic generation of spin orbit coupling
• Metallic "Ferroelectricity" in the Pyrochlore Cd2Re2O7
• Goldstone-Mode Phonon Dynamics in the Pyrochlore Cd2Re2O7
• The nature of the tensor order in Cd2Re2O7

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