Probing the effective mass and fermi velocity of charges by momentum-resolved electron energy loss spectroscopy
Journal
Microscopy
Journal Volume
75
Journal Issue
2
Start Page
157
End Page
163
ISSN
20505698
Date Issued
2026-04
Author(s)
Huang, Chih-Ying
Fongchaiya, Somboon
Hung, Chen-Yu
Chou, Ta-Lei
Huang, Ssu-Yen
Klemm, Mason
Xu, Sijie
Gao, Bin
Dai, Pengcheng
Chu, Ming-Wen
Abstract
The effective mass (m*) and Fermi velocity (vF[jls-end-space/]) are two fundamental gauges of the electronic properties of materials and conventionally measured by magnetotransport characterizations. In this Review, we introduce momentum(q)-resolved electron energy loss spectroscopy (q-EELS) as an alternative method for probing m* and vF[jls-end-space/], and demonstrate its applications in semiconductor Si and semimetal FeGe. The q-EELS methodology is based on the q-dependent plasmon dispersion in the context of the random-phase approximation (RPA) for a free-electron gas (FEG), featuring a quantitative dependence on m* and vF and thus providing the route for retrieving these parameters. We outline the experimental principles for characterizing plasmon dispersions from the optical light line (the order of 10‚àí3‚Äâ√Ö‚àí1) to Brillouin-zone boundaries (the order of √Ö‚àí1), and elucidate the theoretical framework for pertinent elaborations on m* and vF[jls-end-space/]. This work provides both the conceptual and practical guidelines for employing the q-EELS to extract m* and vF of fundamental significances to electronic characteristics of matters.
Subjects
effective mass
electron energy loss spectroscopy
Fermi velocity
momentum
plasmon dispersion
Publisher
Oxford University Press
Type
journal article