ZrTe5 and HfTe5: The heat capacity and derived thermophysical properties from 6 to 350 K

Shaviv, Roey; Westrum, Edgar F.; Fjellvåg, Helmer; Kjekshus, Arne

doi:10.1016/0022-4596(89)90207-7

Cited by 18 publications

(21 citation statements)

References 40 publications

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“…3(e 3 ). This maps a very small Fermi surface, as estimated in previous study [24,25]. As the temperature is increased, the carrier density grows slightly and shows a clear increase above 100 K. Besides, the mobility of the dominant carriers in HfTe 5…”

Section: Engineering Zhejiang University Hangzhou 310027 Chinamentioning

confidence: 67%

“…The sheets of HfTe 5 stack along the b-axis. HfTe 5 has been previously studied for its resistivity anomaly [22,23], thermoelectric properties [24] and quantum oscillations [25,26]. Previous ab initio study has predicted that HfTe 5 and ZrTe 5 crystals are located near the phase boundary between weak and strong topological insulators [27].…”

Section: Engineering Zhejiang University Hangzhou 310027 Chinamentioning

confidence: 99%

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Chiral anomaly and ultrahigh mobility in crystallineHfTe5

Wang

Liu

et al. 2016

Phys. Rev. B

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HfTe 5 is predicted to be a promising platform for studying topological phases. Here through an electrical transport study, we present the first observation of chiral anomaly and ultrahigh mobility in HfTe 5 crystals. Negative magneto-resistivity in HfTe 5 is observed when the external magnetic and electrical fields are parallel (B//E) and quickly disappears once B deviates from the direction of E. Quantitative fitting further confirms the chiral anomaly as the underlying physics. Moreover, by analyzing the conductivity tensors of longitudinal and Hall traces, ultrahigh mobility and ultralow carrier density are revealed in HfTe 5 , which paves the way for potential electronic applications. Chiral anomaly is a quantum anomaly phenomenon that breaks the chiral symmetry and leads to the non-conservation of chiral current [1,2]. This anomaly was proposed to be observed in lattice system in 1983 [3]. Recently, the study of Weyl fermions pushes forward the realization of chiral anomaly in crystals [4][5][6]. In Dirac/Weyl semimetals, the axial current is non-conserved due to the chiral anomaly, and further leads to charge pumping effect between the Weyl nodes with opposite chirality. This anomaly effect is suggested to give rise to negative magneto-resistivity when the magnetic and electrical fields are parallel (B//E) [4]. Related experimental evidences have been intensively pursued in various condensed matter systems Here we present the first electrical transport evidence for the chiral anomaly and the ultrahigh mobility in HfTe 5 crystals.

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Section: Engineering Zhejiang University Hangzhou 310027 Chinamentioning

confidence: 67%

Section: Engineering Zhejiang University Hangzhou 310027 Chinamentioning

confidence: 99%

Chiral anomaly and ultrahigh mobility in crystallineHfTe5

Wang

Liu

et al. 2016

Phys. Rev. B

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“…The thickness of the Al layer was determined using picosecond acoustics . The values of heat capacity for Al and HfTe 5 crystals were taken from the literature …”

Section: Methodsmentioning

confidence: 99%

Thermal Conductivity of HfTe₅: A Critical Revisit

Feng

Yang

et al. 2019

Adv Funct Materials

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Hafnium pentatelluride (HfTe 5 ) has attracted extensive interest due to its exotic electronic, optical, and thermal properties. As a highly anisotropic crystal (layered structure with in-plane chains), it has highly anisotropic electrical-transport properties, but the anisotropy of its thermal-transport properties has not been established. Here, accurate experimental measurements and theoretical calculations are combined to resolve this issue. Time-domain thermoreflectance measurements find a highly anisotropic thermal conductivity, 28:1:8, with values of 11.3 ± 2.2, 0.41 ± 0.04, and 3.2 ± 2.0 W m -1 K -1 along the in-plane a-axis, through-plane b-axis, and in-plane c-axis, respectively. This anisotropy is even larger than what was recently established for ZrTe 5 (12:1:6), but the individual values are somewhat higher, even though Zr has a smaller atomic mass than Hf. Density-functional-theory calculations predict thermal conductivities in good agreement with the experimental data, provide comprehensive insights into the results, and reveal the origin of the apparent anomaly of the relative thermal conductivities of the two pentatellurides. These results establish that HfTe 5 and ZrTe 5 , and by implication their alloys, have highly anisotropic and ultralow through-plane thermal conductivities, which can provide guidance for the design of materials for new directionalheat-management applications and potentially other thermal functionalities.

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“…The super-Eddington state of novae was investigated by Shaviv (1998), who suggested a decrease of the effective opacity of the inhomogeneous atmosphere of novae, which increases the Eddington luminosity well above its standard value, calculated for the Thomson-scattering opacity (see also Shaviv & Dotan 2010.…”

Section: Current View On Super-eddington Luminositymentioning

confidence: 99%

Multiwavelength Modeling of the SED of Nova V339 Del: Stopping the Wind and Long-lasting Super-Eddington Luminosity with Dust Emission

Skopal

2019

ApJ

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During the classical nova outburst, the radiation generated by the nuclear burning of hydrogen in the surface layer of a white dwarf (WD) is reprocessed by the outer material into different forms at softer energies, which distribution in the spectrum depends on the nova age. Using the method of multiwavelength modeling the SED we determined physical parameters of the stellar, nebular and dust component of radiation isolated from the spectrum of the classical nova V339 Del from day 35 to day 636 after its explosion. The transition from the iron-curtain phase to the super-soft source phase (days 35-72), when the optical brightness dropped by 3-4 mag, the absorbing column density fell by its circumstellar component from ∼ 1 × 10 23 to ∼ 1 × 10 21 cm −2 , and the emission measure decreased from ∼ 2 × 10 62 to ∼ 8.5 × 10 60 cm −3 , was caused by stopping-down the mass-loss from the WD. The day 35 model SED indicated an oblate shape of the WD pseudophotosphere and the presence of the dust located in a slow equatorially concentrated outflow. The dust emission peaked around day 59. Its co-existence with the strong super-soft X-ray source in the day 100 model SED constrained the presence of the disk-like outflow, where the dust can spend a long time. Both the models SED revealed a super-Eddington luminosity of the burning WD at a level of 1 − 2 × 10 39 (d/4.5 kpc) 2 erg s −1 , lasting from ∼day 2 to at least day 100.

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ZrTe5 and HfTe5: The heat capacity and derived thermophysical properties from 6 to 350 K

Cited by 18 publications

References 40 publications

Chiral anomaly and ultrahigh mobility in crystallineHfTe5

Chiral anomaly and ultrahigh mobility in crystallineHfTe5

Thermal Conductivity of HfTe₅: A Critical Revisit

Multiwavelength Modeling of the SED of Nova V339 Del: Stopping the Wind and Long-lasting Super-Eddington Luminosity with Dust Emission

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ZrTe5 and HfTe5: The heat capacity and derived thermophysical properties from 6 to 350 K

Cited by 18 publications

References 40 publications

Chiral anomaly and ultrahigh mobility in crystallineHfTe5

Chiral anomaly and ultrahigh mobility in crystallineHfTe5

Thermal Conductivity of HfTe5: A Critical Revisit

Multiwavelength Modeling of the SED of Nova V339 Del: Stopping the Wind and Long-lasting Super-Eddington Luminosity with Dust Emission

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Product

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Thermal Conductivity of HfTe₅: A Critical Revisit