Gap-Opening Transition in Dirac Semimetal ZrTe5

Abstract

We apply 125 Te nuclear magnetic resonance (NMR) spectroscopy to investigate the Dirac semimetal ZrTe 5 . With the NMR magnetic field parallel to the b axis, we observe significant quantum magnetic effects. These include an abrupt drop at 150 K in spin-lattice relaxation rate. This corresponds to a gapopening transition in the Dirac carriers, likely indicating the onset of excitonic pairing. Below 50 K, we see a more negative shift for the Te z bridging site, indicating the repopulation of Dirac levels with spin polarized carriers at these temperatures. This is the previously reported 3D quantum Hall regime; however, we see no sign of a charge density wave as has been proposed.

Site-dependent Local Spin Susceptibility and Low-energy Excitation in a Weyl Semimetal WTe$_2$

“…The result should be confirmed by the band structure calculation taking into account the atomic sites. We obtained the net hyperfine coupling constants H hf (= 22-26 T/µ B ) for Te sites as the linearity coefficient of the K-χ plot, which are comparable to that of ZrTe 5 (∼ 15 T/µ B ) 40) and highlight the predominant onsite hyperfine interaction.…”

Propagation of longitudinal acoustic phonons in ZrTe$_{\boldsymbol{5}}$ exposed to a quantizing magnetic field

“…Furthermore, a CDW amplitude mode can directly be probed by Raman spectroscopy [23]. However, several experiments on ZrTe 5 only show negative evidence for a CDW state [13,16,24]. In this work, we focus on a quantitative analysis of ultrasound measurements that we presented in Ref.…”

Theory of phonon instabilities in Weyl semimetals at high magnetic fields

“…The need for including electron-phonon interactions in theoretical treatments of such systems is illustrated in part by recent high-field measurements in the Weyl semimetal TaAs 26 , where a strong increase in the ultrasonic attenuation at low temperatures has been observed. Likewise, it has been recently suggested that electron-phonon interactions can be important for the field-induced ordered states reported in graphite 17 and in the Dirac semimetal ZrTe 5 49,50 , although the discussion on the presence or absence of order in ZrTe 5 is still ongoing [51][52][53][54] .…”