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5062312 
Journal Article 
Spectroscopic properties of a freestanding MnPS3 single layer 
Kinyanjui, MK; Koester, J; Boucher, F; Wildes, A; Kaiser, U 
2018 
98 
3 
WOS:000438038200006 
Quasi-two-dimensional manganese thiophosphate, MnPS3, is interesting due to its two-dimensional antiferromagnetic structure observed at low temperatures as well as possible technological applications. While the spectroscopic properties of bulk MnPS3 structures have been extensively studied, the spectroscopic characteristics of freestanding MnPS3 layers are yet to be explored. We present an experimental study on the spectroscopic properties of a freestanding MnPS3 single layer obtained through exfoliation from bulk MnPS3. We find that the position of the main peak in the electron-energy-loss spectrum (EELS) is shifted from approximately 19 eV in bulk MnPS3 to 15 eV in single MnPS3 layer. Theoretical calculations show that this peak corresponds to a volume plasmon in bulk MnPS3 and a damped plasmon peak in single-layer MnPS3. In addition, the dispersion of this peak was investigated using momentum-resolved electron-energy-loss spectroscopy. The peak dispersion for the single-layer MnPS3 displays a square-root behavior characteristic of a two-dimensional plasmon. We show that EELS spectra provide both a means to identify single-layer MnPS3 from bulk structures and also show the effects of low dimensionality on the electronic excitations.