Disruption of the Accidental Dirac Semimetal State in ZrTe5 under Hydrostatic Pressure

Abstract

We study the effect of hydrostatic pressure on the magnetotransport properties of the zirconium pentatelluride. The magnitude of resistivity anomaly gets enhanced with increasing pressure, but the transition temperature T * is almost independent of it. In the case of H b, the quasi-linear magnetoresistance decreases drastically from 3300% (9 T) at ambient pressure to 400% (14 T) at 2.5 GPa. Besides, the change of the quantum oscillation phase from topological nontrivial to trivial is revealed around 2 GPa. Both demonstrate that the pressure breaks the accidental Dirac node in ZrTe5. For H c, in contrast, subtle changes can be seen in the magnetoresistance and quantum oscillations. In the presence of pressure, ZrTe5 evolves from a highly anisotropic to a nearly isotropic electronic system, which accompanies with the disruption of the accidental Dirac semimetal state. It supports the assumption that ZrTe5 is a semi-3D Dirac system with linear dispersion along two directions and a quadratic one along the third. PACS numbers:In past few years, the topological quantum materials such as topological insulators (TIs) [1,2], Dirac semimetals [4][5][6][7] and Weyl semimetals [8][9][10][11][12] have stimulated unprecedented research interest both theoretically and experimentally for their unique electronic states. Layered compound ZrTe 5 has been studied for decades due to its large thermoelectric power, mysterious resistivity anomaly and large positive magnetoresistance [13][14][15]. In 2014, Weng et al. predicted that the single-layer ZrTe 5 is a candidate of large-gap quantum spin Hall insulator [16]. On the other hand, the 3D bulk crystal is either a weak or a strong topological insulator, in which the interlayer spacing is believed to play a key role in defining its topological character [16]. Experimental verification, however, remains highly controversial. Scanning tunneling microscopy/ spectroscopy (STM/STS) and angleresolved photoemission spectroscopy (ARPES) measurements detected a bulk band gap with topological edge states at the surface step edge [17,18], hosting the signatures of a weak 3D TI. In contrast, the chiral magnetic effect and non-trivial Berry phase was clearly observed in ZrTe 5 through magneto-transport measurements [19][20][21][22], and the ARPES experiments further identified it to be a 3D Dirac semimetal with only one Dirac node at the Γ point [19,23]. In addition, magnetoinfrared spectroscopy results, such as the linear energy dependence of optical conductivity and Landau level splitting, also support this scenario [24,25]. Very recently, Manzoni et al. find out that the 3D Dirac semimetal phase manifests at the boundary between the weak and strong TI phases [26].Applying pressure is known to be a powerful approach to tune the electronic states and lattice structures without introducing disorder or impurity, which has been widely employed in topological materials. Recently, a pressure-induced semimetal to superconductor transition was observed in ZrTe 5 at 6.2 GPa [27]. However, no quantum osc...

Probing intraband excitations in ZrTe5 : A high-pressure infrared and transport study

“…At pressures above 2.5 GPa, the behavior of the absorption onset is reversed and it drops 4 GPa, before increasing again. Similar nonmonotonic behavior is also observed in T * in function of pressure, 28 where a linear increase of T * (P ) is followed by a decrease of T * around 1.5−2 GPa. The nonmonotonic trend of T * suggests that the onset of absorption at higher pressures becomes influenced not only by the Fermi level, but also by changes in other parameters such as the band gap ∆, or the Fermi velocities along all three axes.…”

Zeeman-splitting-induced topological nodal structure and anomalous Hall conductivity in ZrTe5

“…The sensitivity of the topological phase to small changes of the lattice constant or temperature, places this material as an ideal playground for exploring effects of external stimuli on topological properties. Furthermore, such sensitivity resulted in experimental observations of weak TI 4,11,12 , strong TI 4,13 , and Dirac semimetal phases [14][15][16] in 3D ZrTe 5 .…”

Vanishing quantum oscillations in Dirac semimetal ZrTe 5

“…It has been the most widely used method for determination of the nontrivial Berry phase (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Contrariwise, a shift of the oscillation phase from nontrivial π to zero has been considered as an indication of a possible topological phase transition (18)(19)(20)(21)(22). Note that theories have predicted a rich set of topological phases that a 3D Dirac semimetal can be turned into when subjected to breaking of certain crystal symmetry or time reversal symmetry (23,24).…”