arXiv subjects

A. Pariari

Publications and source records attributed to A. Pariari.

4 recordsLinked to original sources

arXiv2017

Large nonsaturating magnetoresistance and signature of non-degenerate Dirac nodes in ZrSiS

While the discovery of Dirac and Weyl type excitations in electronic systems is a major breakthrough in recent condensed matter physics, finding appropriate materials for fundamental physics and technological applications, is an experimental challenge. In all the reported materials, linear dispersion survives only up to a few hundred meV from the Dirac or Weyl nodes. On the other hand, real materials are subject to uncontrolled doping during preparation and thermal effect near room temperature can hinder the rich physics. In ZrSiS, ARPES measurements have shown an unusually robust linear dispersion (up to $\sim$2 eV) with multiple non-degenerate Dirac nodes. In this context, we present the magnetotransport study on ZrSiS crystal, which represents a large family of materials (\textit{WHM} with \textit{W} = Zr, Hf; \textit{H} = Si, Ge, Sn; \textit{M} = O, S, Se, Te) with identical band topology. Along with extremely large and non-saturating magnetoresistance (MR), $\sim$ 1.4 $\times$ 10$^{5}$ \% at 2 K and 9 T, it shows strong anisotropy depending on the direction of the magnetic field. Quantum oscillation and Hall effect measurements have revealed large hole and small electron Fermi pockets. Non-trivial $π$ Berry phase confirms the Dirac fermionic nature for both types of charge carriers. The long-sought relativistic phenomenon of massless Dirac fermions, known as Adler-Bell-Jackiw chiral anomaly, has also been observed.

cond-mat.mtrl-sci↗

arXiv2016

Tuning the scattering mechanism in three-dimensional Dirac semimetal Cd$_{3}$As$_{2}$

To probe the charge scattering mechanism in Cd$_{3}$As$_{2}$ single crystal, we have analyzed the temperature and magnetic field dependence of the Seebeck coefficient ($S$). The large saturation value of $S$ at high field clearly demonstrates the linear energy dispersion of three-dimensional Dirac fermion. A wide tunability of the charge scattering mechanism has been realized by varying the strength of the magnetic field and carrier density via In doping. With the increase in magnetic field, the scattering time crosses over from being nearly energy independent to a regime of linear dependence. On the other hand, the scattering time enters into the inverse energy-dependent regime and the Fermi surface strongly modifies with 2\% In doping at Cd site. With further increase in In content from 2 to 4\%, we did not observe any Shubnikov-de Haas oscillation up to 9 T field, but the magnetoresistance is found to be quite large as in the case of undoped sample.

cond-mat.str-el↗

arXiv2015

Magnetic field induced drastic violation of Wiedemann-Franz law in Dirac semimetal Cd$_{3}$As$_{2}$

The journey through the nontrivial band topology beyond the conventional band structure has resulted in the recent discovery of three-dimensional Dirac semimetal phase in Na$_{3}$Bi and Cd$_{3}$As$_{2}$. The bulk state of which is semi-metallic obeying linear energy dispersion, while the surface state is topology protected Fermi arc. Due to the unique band topology, they show different exotic electronic properties of both fundamental and technological interest. From electrical and thermal transport measurements, we have demonstrated a remarkable violation of Wiedemann-Franz law (WFL) under application of magmatic field in Cd$_{3}$As$_{2}$ and the violation becomes more and more drastic with increasing magnetic field strength. Whereas the validity of WFL is the key feature of Landau Fermi-liquid theory in metal, the notion of quasiparticles is the building block to this theory. This implies that the fundamental concept of Landau quasiparticle no longer holds in Cd$_{3}$As$_{2}$ in presence of magnetic field. The continuous break down of Landau quasiparticle framework with field introduces a concept of field induced quantum critical point (QCP) as in the case of heavy fermion compounds YbRh$_{2}$Si$_{2}$, Sr$_{3}$Ru$_{2}$O$_{7}$, etc.

cond-mat.str-el↗

arXiv2015

Probing the Fermi Surface of 3D Dirac Semimetal Cd$_{3}$As$_{2}$ through de Haas-van Alphen Technique

We have observed Shubnikov-de Haas and de Haas-van Alphen effect in the single crystals of three dimensional Dirac semimetal Cd$_{3}$As$_{2}$ upto 50 K, traceable at field as low as 2 T and 1 T, respectively. The values of Fermi wave vector, Fermi velocity, and effective cyclotron mass of charge carrier, calculated from both the techniques, are close to each other and match well with the earlier reports. However, the de Haas-van Alphen effect clearly reflects the existence of two different Fermi surface cross-sections along certain direction and a non-trivial Berry's phase which is the signature of 3D Dirac Fermion in Cd$_{3}$As$_{2}$.

cond-mat.str-el↗