Metal-chalcogen bond-length induced electronic phase transition from semiconductor to topological semimetal in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Zr</mml:mi><mml:msub><mml:mi>X</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>X</mml:mi><mml:mo>=</mml:mo><mml:mi>Se</mml:mi></mml:math> and Te)
Indrani Kar, Joydeep Chatterjee, Luminita Harnagea, Yevhen Kushnirenko, Alexander Fedorov, Deepika Shrivastava, B. Büchner, Priya Mahadevan, S. Thirupathaiah
Abstract
Topological transition-metal dichalcogenides have been the center of research interests in materials science, recent days, due to their potential applications in spintronics, optoelectronics, and quantum computations. In this paper, using angle resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations, we systematically studied the low-energy electronic structure of bulk ${\mathrm{ZrTe}}_{2}$. ARPES studies on ${\mathrm{ZrTe}}_{2}$ demonstrate free charge carriers at the Fermi level, which is further confirmed by the DFT calculations. An equal hole and electron carrier density estimated from the ARPES data points to ${\mathrm{ZrTe}}_{2}$ being a semimetal. The DFT calculations further suggest a band inversion between Te $p$ and Zr $d$ states at the $\mathrm{\ensuremath{\Gamma}}$ point, hinting at the nontrivial band topology in ${\mathrm{ZrTe}}_{2}$. Thus our studies suggest that ${\mathrm{ZrTe}}_{2}$ is a topological semimetal. Also, a comparative band structure study is done on ${\mathrm{ZrSe}}_{2}$, which shows a semiconducting nature of the electronic structure with an indirect band gap of 0.9 eV between $\mathrm{\ensuremath{\Gamma}}(A)$ and $M(L)$ high-symmetry points. Below we show that the metal-chalcogen bond length plays a critical role in the electronic phase transition from a semiconductor to a topological semimetal ingoing from ${\mathrm{ZrSe}}_{2}$ to ${\mathrm{ZrTe}}_{2}$.