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FIELD
Phys:Condensed Matter Physics
DATE
Jan 20 (Mon), 2025
TIME
11:00 ~ 12:30
PLACE
1424
SPEAKER
Han, SangEun
HOST
Hwang, Kyusung
INSTITUTE
Simon Fraser University
TITLE
Quantum impurity model for two-stage multipolar ordering and Fermi surface reconstruction
ABSTRACT
Classification and understanding of quantum phase transitions and critical phenomena in itinerant electron systems are outstanding questions in quantum materials research. Recent experiments on heavy fermion systems with higher-rank multipolar local moments provide a new platform to study such questions. In particular, experiments on Ce3Pd20(Si,Ge)6 show novel quantum critical behaviors via two consecutive magnetic field-driven quantum phase transitions. At each transition, the derivative of the Hall conductivity jumps discontinuously, which was attributed to sequential Fermi surface reconstructions. Motivated by this discovery, we consider an effective quantum impurity model of itinerant electrons coupled to local dipolar, quadrupolar, and octupolar moments arising from Ce3+ ions. Using renormalization group analyses, we demonstrate that two-stage multipolar ordering and Fermi surface reconstruction arise depending on which multipolar moments participate in the Fermi surface and which other moments are decoupled via Kondo destruction.
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