Approaching three-dimensional quantum Hall effect in bulk HfTe5

Abstract

The discovery of quantum Hall effect in two-dimensional (2D) electronic systems inspired the topological classifications of electronic systems 1,2 . By stacking 2D quantum Hall effects with interlayer coupling much weaker than the Landau level spacing, quasi-2D quantum Hall effects have been experimentally observed 3~7 , due to the similar physical origin of the 2D counterpart. Recently, in a real 3D electronic gas system where the interlayer coupling is much stronger than the Landau level spacing, 3D quantum Hall effect has been observed in ZrTe5 8 . In this Letter, we report the electronic transport features of its sister bulk material, i.e., HfTe5, under external magnetic field. We observe a series of plateaus in Hall resistance ρxy as magnetic field increases until it reaches the quantum limit at 1~2 Tesla. At the plateau regions, the longitudinal resistance ρxx exhibits local

Unconventional Hall response in the quantum limit of HfTe5

“…23 ). The height of the last integer plateau is given by ( h / e 2 ) π / k F, z , similar to as reported in the literature for the 3D IQHE 21 , 22 . The plateaus are most pronounced at low temperatures, but still visible up to T = 30 K (Fig.…”

“…For example, signatures of the integer quantum Hall effect (IQHE) have been found in quasi-2D semiconducting multilayer lattices 15 , Bechgaards salts 16,17 , η-Mo 4 O 11 18 , n-doped Bi 2 Te 3 19 , and EuMnBi 2 20 , in which the layered crystal structure itself supplies the stack of 2D systems. Very recently, the QHE has also been observed in 3D graphite films 5 , bulk ZrTe 5 21 , and HfTe 5 samples 22 . In graphite, the imposed periodic superstructure has been attributed to the formation of standing electron waves.…”

“…Both materials share an orthorhombic crystal structure and a single elliptical 3D Fermi surface, comprising less than 1% of the Brillouin zone and hosting massive Dirac Fermions with almost linearly dispersing bands in the vicinity of the Fermi level (see Supplementary Information for details). These specific properties have been considered essential for the observation of the 3D IQHE in both materials [21][22][23] . Moreover, recent progress in ZrTe 5 21 and HfTe 5 32 single-crystal growth has enabled a Hall mobility μ that exceeds 100,000 cm 2 V −1 s −1 at low temperatures (<4 K) (see "Methods" section and Supplementary Information S1).…”

Correlated oxide Dirac semimetal in the extreme quantum limit

“…Thus, one of the carriers could reach the quantum limit, although strained SrNbO 3 has multiple carriers. The compounds ZrTe 5 and HfTe 5 are other good examples in which only one carrier among multiple carriers shows quantum limit behavior (63,64).…”

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

“…The three-dimensional (3D) compound zirconium pentatelluride (ZrTe 5 ) has been extensively studied due to its large negative magnetoresistivity [1,2], thermoelectric properties [3][4][5] and because it possibly exhibits a variety of topological phases, including weak and strong topological insulator and Dirac semimetal phases [6][7][8][9][10]. A focus of recent discussions has been the observation of plateau-like features in the transverse resistivity accompanied by minima in the longitudinal resistivity both in ZrTe 5 [11][12][13] and the structurally similar HfTe 5 [14,15]. These plateau-like features have been proposed to be linked to the formation of a periodic modulation of electron density, a charge-density wave (CDW), and to a truly quantized Hall effect in three dimensions.…”