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Title: Electronic and structural ground state of heavy alkali metals at high pressure

Here, alkali metals display unexpected properties at high pressure, including emergence of low symmetry crystal structures, that appear to occur due to enhanced electronic correlations among the otherwise nearly-free conduction electrons. We investigate the high pressure electronic and structural ground state of K, Rb, and Cs using x-ray absorption spectroscopy and x-ray diffraction measurements together with ab initio theoretical calculations. The sequence of phase transitions under pressure observed at low temperature is similar in all three heavy alkalis except for the absence of the oC84 phase in Cs. Both the experimental and theoretical results point to pressure-enhanced localization of the valence electrons characterized by pseudo-gap formation near the Fermi level and strong spd hybridization. Although the crystal structures predicted to host magnetic order in K are not observed, the localization process appears to drive these alkalis closer to a strongly correlated electron state.
 [1] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Argonne National Lab. (ANL), Argonne, IL (United States); Washington Univ., St. Louis, MO (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Washington Univ., St. Louis, MO (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Lab. Nacional de Luz Sincrotron, Sao Paulo (Brazil); UNICAMP, Sao Paulo (Brazil)
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
NA0002006; AC02-06CH11357; FG02-99ER45775; FC52-08NA28554; NA0001974
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 91; Journal Issue: 8; Journal ID: ISSN 1098-0121
American Physical Society (APS)
Research Org:
Carnegie Institution of Washington, Washington, D.C. (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States