Observation of Magnetic Field-Tuned Quantum Phase Transition in Intermetallic CeAg$_{2}$Ge$_{2}$

ORAL

Abstract

Quantum phase transition arises either due to the competition between Kondo screening and long range RKKY-type interaction or, the spin density wave (SDW) instability of the Fermi surface at the quantum critical point. We have performed neutron scattering measurements on single crystal CeAg2Ge2 and observed the SDW-type quantum phase transition with magnetic field as tuning parameter. CeAg2Ge2 crystallizes in a ThCr2Si2-type tetragonal crystal structure and undergoes an antiferromagnetic transition at TN = 4.6 K. Detail measurements of Q-vectors associated with long-range order and the numerical modeling of the data revealed the propagation of amplitude modulated spin density wave in this compound. With magnetic field as tuning parameter, the variation of magnetic ordering moment across 2 T field was clearly observed. Experimental data of CeAg$_{2}$Ge$_{2}$ will be discussed along with other Ce-based rare earth heavy fermion compounds which exhibit quantum criticality at low temperature.

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Authors

  • Deepak Singh

    National Institute of Standard and Technology, NIST

  • Arumugam Thamizhavel

    Dept. of CMP and MS, Tata Institute of Fundamental Research, Colaba, Mumbai, India, Tata Institute of Fundamental Research

  • Sung Chang

    NCNR, NIST, National Institute of Standard and Technology

  • J.W. Lynn

    NIST, National Institute of Standard and Technology, NIST Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg, MD 20899