Pressure-tuned Frustration of Magnetic Coupling in Elemental Europium

Journal Article · 05 February 2019 · Physical Review Letters

DOI: https://doi.org/10.1103/PhysRevLett.122.057201 · OSTI ID:1544120

Pi, Shu-Ting ^[1]; Savrasov, Sergey Y. ^[1]; Pickett, Warren E. ^[1]

---

1. Univ. of California, Davis, CA (United States)

Applying linear response and the magnetic force theorem in correlated density functional theory, the intersublattice exchange constants of antiferromagnetic Eu are calculated and found to vanish near the pressure of P_c = 82 GPa, just where magnetic order is validated experimentally to be lost. The Eu 4f⁷ moment remains unchanged at high pressure, again in agreement with spectroscopic measurements, leaving the picture of perfect frustration of interatomic Ruderman-Kittel-Kasuya-Yoshida couplings in a broad metallic background, leaving a state of electrons strongly exchange coupled to arbitrarily oriented, possibly quasistatic local moments. This strongly frustrated state gives way to superconductivity at T_c = 1.7 K, observed experimentally. Furthermore, these phenomena, and free energy considerations related to correlations, suggest an unusual phase of matter that is discussed within the scenarios of the Doniach Kondo lattice phase diagram, the metallic spin glass class, and itinerant spin liquid or spin gas systems.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC02-05CH11231; NA0002908
• OSTI ID: 1544120
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 5 Vol. 122; ISSN 0031-9007; ISSN PRLTAO
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English