Evolution of static charge density wave order, amplitude mode dynamics, and suppression of Kohn anomalies at the hysteretic transition in EuTe4

• DOI: 10.1103/physrevb.107.024101
• Publication Date: 2023-01-04T15:02:03Z
• Authors: Ranjana Rathore; Abhishek Pathak; Mayanak K. Gupta; Ranjan Mittal; Ruta Kulkarni; A. Thamizhavel; Himanshu Singhal; Ayman H. Said; Dipanshu Bansal
• Keywords: Charge Density Wave; Lattice (music); Metastability

Charge density wave (CDW) induces periodic spatial modulation of the charge that is commensurate or incommensurate with host lattice periodicity, and leads to partial complete electronic band-gap opening at Fermi level (${E}_{\mathrm{F}}$). The recent finding unconventional hysteresis within CDW phase ${\mathrm{EuTe}}_{4}$, not observable in other rare-earth tellurides $R{\mathrm{Te}}_{n}$ ($n=2$, 3), has highlighted role relative distortion weakly coupled Te layers. However, detailed structural dynamical characterization on hysteretic transition lacking. Here we report static order, dynamics amplitude mode, their evolution using meV resolution elastic inelastic x-ray scattering. We discover previously unidentified multiple vectors ${\mathbf{q}}_{\mathrm{CDW}}$ along all three crystallographic axes. Importantly, find reported $b$-axis peak interlayer consequently co-occurs doubling unit cell $c$ axis. confirm presence competing $a$-axis order but found it be four orders magnitude weaker than CDW. Furthermore, observe Kohn anomalies driven by surface nesting hidden nesting, confirming earlier reports based susceptibility simulations. mode are suppress transition, suggesting nondegenerate metastable states, which identify from scattering measurements