Consistency between reflection momentum-resolved electron energy loss spectroscopy and optical spectroscopy measurements of the long-wavelength density response of Bi 2 Sr 2 CaCu 2 O 8 + x

Journal Article · 04 January 2024 · Physical Review. B

DOI: https://doi.org/10.1103/physrevb.109.045108 · OSTI ID:2338113

Chen, Jin  ^[1]; Guo, Xuefei ^[1]; Boyd, Christian ^[1]; Bettler, Simon ^[1]; Kengle, Caitlin ^[1]; Chaudhuri, Dipanjan  ^[1]; Hoveyda, Farzaneh  ^[1]; Husain, Ali  ^[1]; Schneeloch, John ^[2]; Gu, Genda  ^[2]; Phillips, Philip ^[1]; Uchoa, Bruno ^[3]; Chiang, Tai-Chang ^[1]; Abbamonte, Peter  ^[1]

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1. University of Illinois at Urbana-Champaign, IL (United States)
2. Brookhaven National Laboratory (BNL), Upton, NY (United States)
3. University of Oklahoma, Norman, OK (United States)

The density fluctuation spectrum captures many fundamental properties of strange metals. Using momentum-resolved electron energy-loss spectroscopy (M-EELS), we recently showed that the density response of the strange metal Bi₂Sr₂CaCu₂O_8+x (Bi-2212) at large momentum, q, exhibits a constant-in-frequency continuum reminiscent of the marginal Fermi liquid (MFL) hypothesis of the late 1980s. However, reconciling this observation with infrared (IR) optics experiments, which show a well-defined plasmon excitation at q ~ 0, has been challenging. Here we report M-EELS measurements of Bi-2212 using 4× improved momentum resolution, allowing us to reach the optical limit. For momenta q < 0.04 r.l.u., the M-EELS data show a plasmon feature that is quantitatively consistent with IR optics. For q > 0.04 r.l.u., the spectra become incoherent with an MFL-like, constant-in-frequency form. Here we speculate that, at finite frequency, ω, and nonzero q, some attribute of this Planckian metal randomizes the probe electron, causing it to lose information about its own momentum.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); Gordon and Betty Moore Foundation; National Science Foundation (NSF); USDOE
• Grant/Contract Number: SC0012704; SC0021238; GBMF9452; DMR-2024864
• OSTI ID: 2338113
• Alternate ID(s): OSTI ID: 2278740
• Report Number(s): BNL-225506-2024-JAAM; TRN: US2410433
• Journal Information: Physical Review. B, Vol. 109, Issue 4; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English