Non-Quadratic Transverse Magnetoresistance in the Nodal Line Dirac Semimetal InBi

Abstract We study various thermodynamic and transport properties of a holographic model of a nodal line semimetal (NLSM) at finite temperature, including the quantum phase transition to a topologically trivial phase, with Dirac semimetal-like conductivity. At zero temperature, composite fermion spectral functions obtained from holography are known to exhibit multiple Fermi surfaces. Similarly, for the holographic NLSM we observe multiple nodal lines instead of just one. We show, however, that as the temperature is raised these nodal lines broaden and disappear into the continuum one by one, so there is a finite range of temperatures for which there is only a single nodal line visible in the spectrum. We compute several transport coefficients in the holographic NLSM as a function of temperature, namely the charge and thermal conductivities, and the shear viscosities. By adding a new non-linear coupling to the model we are able to control the low frequency limit of the electrical conductivity in the direction orthogonal to the plane of the nodal line, allowing us to better match the conductivity of real NLSMs. The boundary quantum field theory is anisotropic and therefore has explicitly broken Lorentz invariance, which leads to a stress tensor that is not symmetric. This has important consequences for the energy and momentum transport: the thermal conductivity at vanishing charge density is not simply fixed by a Ward identity, and there are a much larger number of independent shear viscosities than in a Lorentz-invariant system.

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A Dirac semimetal phase diagram of the binary compound CuI(R-3m)

Journal of Physics and Chemistry of Solids ◽

10.1016/j.jpcs.2019.03.008 ◽

2019 ◽

Vol 131 ◽

pp. 62-68

Author(s):

Xinxin Zhao

Keyword(s):

Phase Diagram ◽

Binary Compound ◽

Dirac Semimetal

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Computation and data driven discovery of topological phononic materials

Nature Communications ◽

10.1038/s41467-021-21293-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jiangxu Li ◽

Jiaxi Liu ◽

Stanley A. Baronett ◽

Mingfeng Liu ◽

Lei Wang ◽

...

Keyword(s):

High Throughput Screening ◽

Electronic System ◽

Nodal Line ◽

Data Driven ◽

Single Type ◽

Type I ◽

Structure Property ◽

Topological Quantum ◽

Data Driven Approach ◽

Spin Electronic

AbstractThe discovery of topological quantum states marks a new chapter in both condensed matter physics and materials sciences. By analogy to spin electronic system, topological concepts have been extended into phonons, boosting the birth of topological phononics (TPs). Here, we present a high-throughput screening and data-driven approach to compute and evaluate TPs among over 10,000 real materials. We have discovered 5014 TP materials and grouped them into two main classes of Weyl and nodal-line (ring) TPs. We have clarified the physical mechanism for the occurrence of single Weyl, high degenerate Weyl, individual nodal-line (ring), nodal-link, nodal-chain, and nodal-net TPs in various materials and their mutual correlations. Among the phononic systems, we have predicted the hourglass nodal net TPs in TeO3, as well as the clean and single type-I Weyl TPs between the acoustic and optical branches in half-Heusler LiCaAs. In addition, we found that different types of TPs can coexist in many materials (such as ScZn). Their potential applications and experimental detections have been discussed. This work substantially increases the amount of TP materials, which enables an in-depth investigation of their structure-property relations and opens new avenues for future device design related to TPs.

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