Trigonal distortion and charge transfer in zigzag-antiferromagnet metal phosphorus trisulfides

Aldrin Chang^1,9*, Liang-Wei Lan¹, Yao-Jui Chan^1,4, Chia-Nung Kuo², Jau-Wern Chiou³, Ting Chen¹, Chih-Heng Huang¹, Tzu-Hung Chuang⁵, Der-Hsin Wei⁵, Chin-Shan Lue^2,6,7, Wai-Faung Pong⁸, Chien-Cheng Kuo¹

¹Department of Physics, National Sun Yat-sen University, Kaohsiung City, Taiwan
²Department of Physics, National Cheng Kung University, Tainan City, Taiwan
³Department of Applied Physics, National University of Kaohsiung, Kaohsiung City, Taiwan
⁴Institute of Physics, Academia Sinica, Taipei City, Taiwan
⁵National Synchrotron Radiation Research Center, Hsinchu City, Taiwan
⁶Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei, Taiwan
⁷Program on Key Materials, Academy of Innovative Semiconductor and Sustainable Manufacturing, National Cheng Kung University, Tainan City, Taiwan
⁸Department of Physics, Tamkang University, New Taipei City, Taiwan
⁹Physics Department, Technological University of the Philippines, Manila City, Philippines

* Presenter:Aldrin Chang, email:phyaldrin@gmail.com

Trigonal distortion in the Fe-S local crystalline environment of FePS₃ was resolved using x-ray absorption spectroscopy. X-ray linear dichroism was performed in both the paramagnetic and antiferromagnetic phase and in combination with semi-empirical calculations, a lower-than-cubic symmetry was needed to explain the non-vanishing feature in the dichroism spectra. Energy splitting of 0.35 eV between the a_1g and e_g±^π was estimated contrary to previous reports purporting a negligible trigonal-field splitting. Negative charge-transfer energy in NiPS₃ was probed using XAS and charge transfer multiplet calculations. The recorded dipole-allowed transition in XAS that was proven to be charge-transfer energy sensitive was further experimentally verified by resonant inelastic x-ray scattering to be indeed charge-transfer in origin. The observation of these properties in these 2D magnetic van der Waals materials will prove to be crucial for its potential device and spintronic applications.

Keywords: trigonal distortion, charge transfer, x-ray absorption spectroscopy, resonant inelastic x-ray scattering