Anomalous Shubnikov-de Haas effect and observation of the Bloch-Gr\"uneisen temperature in the Dirac semimetal ZrTe5

TL;DR

This study observes an anomalous suppression of quantum oscillations in ZrTe5 at low temperatures, linked to electron-phonon interactions and the Bloch-Gr"uneisen temperature, revealing insights into electron-lattice decoupling.

Contribution

It reports the first observation of suppressed Shubnikov-de Haas oscillations in ZrTe5 linked to electron-phonon decoupling at the Bloch-Gr"uneisen temperature.

Findings

Suppression of SdH oscillations in single FS sheet ZrTe5 at sub-kelvin temperatures.

Recovery of Lifshitz-Kosevich behavior in multi-sheet FS samples.

Abrupt increase in electronic viscosity at T_BG.

Abstract

Appearance of quantum oscillations (QO) in both thermodynamic and transport properties of metals at low temperatures is the most striking experimental consequence of the existence of a Fermi surface (FS). The frequency of these oscillations and the temperature dependence of their amplitude provides essential information about the FS topology and fermionic quasiparticle properties. Here, we report the observation of an anomalous suppression of the QO amplitude seen in resistivity (Shubnikov de-Haas effect) at sub-kelvin temperatures in ZrTe5 samples with a single small FS sheet comprising less than 5% of the first Brillouin zone. By comparing these results with measurements of the magneto-acoustic QO and the recovery of the usual Lifshitz-Kosevich behavior of the Shubnikov de-Haas (SdH) effect in ZrTe$_5$ samples with a multi-sheet FS, we show that the suppression of the SdH effect originates from a decoupling of the electron liquid from the lattice. On crossing the so-called Bloch-Gr\"uneisen temperature, T$_BG$, electron-phonon scattering becomes strongly suppressed and in the absence of Umklapp scattering the electronic liquid regains Galilean invariance. In addition, we show, using a combination of zero-field electrical conductivity and ultrasonic-absorption measurements, that entering this regime leads to an abrupt increase of electronic viscosity.