Anomalous Hall effect induced by Berry curvature in the topological nodal-line van der Waals ferromagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Fe</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:msub><mml:mi>GeTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>
Satyabrata Bera, Sudipta Chatterjee, Subhadip Pradhan, Suman Kalyan Pradhan, Sk Kalimuddin, Arnab Bera, Ashis Nandy, Mintu Mondal
Abstract
The exploration of nontrivial transport phenomena associated with the interplay between magnetic order and spin-orbit coupling (SOC), particularly in van der Waals (vdW) systems, has gained a resurgence of interest due to their easy exfoliation, ideal for two-dimensional (2D) spintronics. We report the near room temperature quasi-2D ferromagnet, ${\mathrm{Fe}}_{4}{\mathrm{GeTe}}_{2}$ from the iron-based vdW family (${\mathrm{Fe}}_{n}{\mathrm{GeTe}}_{2}, n=3$,4,5), exhibiting a large anomalous Hall conductivity (AHC), ${\ensuremath{\sigma}}_{xy}^{A}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}\phantom{\rule{0.16em}{0ex}}490\phantom{\rule{0.16em}{0ex}}{\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}1}{\text{cm}}^{\ensuremath{-}1}$ at 2 K. The near quadratic behavior of anomalous Hall resistivity (${\ensuremath{\rho}}_{xy}^{A}$) with the longitudinal resistivity (${\ensuremath{\rho}}_{xx}$) suggests that a dominant AHC contribution is coming from an intrinsic Berry curvature (BC) mechanism. Concomitantly, the electronic structure calculations reveal a large BC arising from SOC induced gapped nodal lines around the Fermi level, governing such large AHC property. Moreover, we also report an exceptionally large anomalous Hall angle ($\ensuremath{\simeq}10.6$%) and Hall factor ($\ensuremath{\simeq}0.22 {\mathrm{V}}^{\ensuremath{-}1}$) values which, so far, are the largest in compared to those for other members in this vdW family.