Investigation of nonlinear and nonreciprocal transport phenomena in ferromagnetic untwinned Weyl metal SrRuO3/SrTiO3(001) thin films

Uddipta Kar^1*, Elisha Cho-Hao Lu¹, Akhilesh Kr. Singh¹, P. V. Sreenivasa Reddy², Youngjoon Han⁴, Xinwei Li⁴, Cheng-Tung Cheng¹, Song Yang⁵, Chun-Yen Lin⁵, I-Chun Cheng⁶, Chia-Hung Hsu⁵, D. Hsieh⁴, Wei-Cheng Lee³, Guang-Yu Guo^2,7, Wei-Li Lee¹

¹Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
²Department of Physics, National Taiwan University, Taipei 10617, Taiwan
³Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York 13902, USA
⁴Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
⁵Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
⁶Physics Division, National Center for Theoretical Sciences, Taipei 10617, Taiwan
⁷Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan

* Presenter:Uddipta Kar, email:uddiptakar2024@gmail.com

Identifying unique charge transport characteristics arising from nontrivial bulk and surface states provided rich physics and functionalities. Here, we report a large nonlinear and nonreciprocal transport phenomena in both the longitudinal and transverse channels in untwinned thin films of Weyl metal SrRuO3/SrTiO3(001) substrate. Through comprehensive measurements with the application of bias currents along different orientations relative to the orthorhombic [001]o crystalline axes, we have observed that the magnitude of non-linear Hall signals in the transverse channel follows a sinα dependency at low temperatures. Here, α represents the angle between the direction of the bias current and the orthorhombic [001]o axis, and o represents the orthorhombic structural phase. Notably, these signals reach their maximum when the current aligns with the orthorhombic [11 ̅0]o direction. Conversely, in the longitudinal channel, the magnitude of nonlinear and nonreciprocal signals reaches its maximum when the bias current is aligned with the [001]o direction, while it completely disappears when the current is directed along [11 ̅0]o. The α-dependent nonlinear and nonreciprocal signals observed in both the longitudinal and transverse channels provide insight into a time-reversal symmetry-broken magnetic Weyl phase featuring an effective Berry curvature dipole oriented along [11 ̅0]o, which is accompanied by one-dimensional (1D) chiral edge modes along the [001]o direction. The detailed topological origin based on the calculated band structure will be presented and discussed.

Keywords: Nonlinear and nonlocal transport, Weyl metal, Berry curvature dipole, chiral edge mode, SrRuO3(t)/SrTiO3