Thermoelectric power of HfTe5 and ZrTe5

Jones, Toinetta; Fuller, W. W.; Wieting, Terence J.; Lévy, F.

doi:10.1016/0038-1098(82)90008-4

Cited by 116 publications

(92 citation statements)

References 11 publications

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“…Layered material ZrTe 5 has been known for decades due to its large thermoelectric power 36,37 , resistivity anomaly 38 and quantum oscillations 39,40 . Earlier experimental results exhibited an extremely small ellipsoidal Fermi surface 40 with small effective mass in the chain direction.…”

Section: Introductionmentioning

confidence: 99%

Transport evidence for the three-dimensional Dirac semimetal phase inZrTe5

et al. 2016

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Topological Dirac semimetal is a newly discovered class of materials which has attracted intense attentions. This material can be viewed as a three-dimensional (3D) analog of graphene and has linear energy dispersion in bulk, leading to a range of exotic transport properties. Here we report direct quantum transport evidence of the 3D Dirac semimetal phase of layered material ZrTe 5 by angular dependent magnetoresistance measurements under high magnetic fields up to 31 T. We observed very clear negative longitudinal magnetoresistance induced by chiral anomaly under the condition of the magnetic field aligned only along the current direction. Pronounced Shubnikov-de Hass (SdH) quantum oscillations in both longitudinal magnetoresistance and transverse Hall resistance were observed, revealing anisotropic light cyclotron masses and high mobility of the system. In particular, a nontrivial π-Berry phase in the SdH oscillations gives clear evidence for 3D Dirac semimetal phase. Furthermore, we observed clear Landau level splitting under high magnetic field, suggesting possible splitting of the Dirac point into Weyl points due to broken time reversal symmetry. Our results indicate that ZrTe 5 is an ideal platform to study 3D massless Dirac and Weyl fermions in a layered compound.

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Section: Introductionmentioning

confidence: 99%

Transport evidence for the three-dimensional Dirac semimetal phase inZrTe5

et al. 2016

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“…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].…”

Section: Pacs Numbersmentioning

confidence: 99%

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

Zhang¹,

Guo²,

Zhu³

et al. 2017

Phys. Rev. Lett.

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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...

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“…ZrTe 5 has been studied for a long time due to its large thermoelectric power (8,9), resistivity anomaly (10,11), and large positive magnetoresistance (12). Recent theoretical works (13,14) have proposed that single-layer ZrTe 5 is a large gap quantum spin hall insulator, but the bulk ZrTe 5 behaves between the strong and weak topological insulator.…”

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confidence: 99%

Pressure-induced superconductivity in a three-dimensional topological material ZrTe ₅

Zhou

Ning

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

147

105

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As a new type of topological materials, ZrTe 5 shows many exotic properties under extreme conditions. Using resistance and ac magnetic susceptibility measurements under high pressure, while the resistance anomaly near 128 K is completely suppressed at 6.2 GPa, a fully superconducting transition emerges. The superconducting transition temperature T c increases with applied pressure, and reaches a maximum of 4.0 K at 14.6 GPa, followed by a slight drop but remaining almost constant value up to 68.5 GPa. At pressures above 21.2 GPa, a second superconducting phase with the maximum T c of about 6.0 K appears and coexists with the original one to the maximum pressure studied in this work. In situ high-pressure synchrotron X-ray diffraction and Raman spectroscopy combined with theoretical calculations indicate the observed two-stage superconducting behavior is correlated to the structural phase transition from ambient Cmcm phase to high-pressure C2/m phase around 6 GPa, and to a mixture of two high-pressure phases of C2/m and P-1 above 20 GPa. The combination of structure, transport measurement, and theoretical calculations enable a complete understanding of the emerging exotic properties in 3D topological materials under extreme environments.high pressure | Dirac semimetals | superconductivity | synchrotron X-ray diffraction S ince the first report of topological insulator, an extensive attention in recent years has been focused on newly emergent Dirac materials including topological insulators (1-3), Dirac semimetals (4, 5), and Weyl semimetals (5-7) for their unique quantum phenomena. ZrTe 5 has been studied for a long time due to its large thermoelectric power (8, 9), resistivity anomaly (10, 11), and large positive magnetoresistance (12). Recent theoretical works (13,14) have proposed that single-layer ZrTe 5 is a large gap quantum spin hall insulator, but the bulk ZrTe 5 behaves between the strong and weak topological insulator. These predictions spark the renewed interest in the investigation of its Dirac and topological characters. Indeed, the magnetotransport experiments (15) have observed the chiral magnetic effect, both angle-resolved photoemission spectroscopy (15) and magneto-infrared spectroscopy (16, 17) study show the electronic structure of ZrTe 5 is similar with other three-dimensional (3D) Dirac semimetals like Na 3 Bi (18-20) and Cd 3 As 2 (21-25). These results suggest that ZrTe 5 is a very promising system that hosts topological properties and might help to pave a new way for further experimental studies of topological phase transitions.As one of the fundamental state parameters, high pressure is an effective, clean way to tune lattice as well as electronic states, especially in quantum states (26)(27)(28). In this work, by performing resistance and ac magnetic susceptibility measurements on ZrTe 5 single crystal at various pressures up to 68.5 GPa, a superconducting transition at 1.8 K was first noticed at a pressure of 6.2 GPa. It was interesting to notice that the occurrence of the metallic pha...

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Thermoelectric power of HfTe5 and ZrTe5

Cited by 116 publications

References 11 publications

Transport evidence for the three-dimensional Dirac semimetal phase inZrTe5

Transport evidence for the three-dimensional Dirac semimetal phase inZrTe5

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

Pressure-induced superconductivity in a three-dimensional topological material ZrTe ₅

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Thermoelectric power of HfTe5 and ZrTe5

Cited by 116 publications

References 11 publications

Transport evidence for the three-dimensional Dirac semimetal phase inZrTe5

Transport evidence for the three-dimensional Dirac semimetal phase inZrTe5

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

Pressure-induced superconductivity in a three-dimensional topological material ZrTe 5

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Pressure-induced superconductivity in a three-dimensional topological material ZrTe ₅