Suppression of antiferromagnetic order and strong ferromagnetic spin fluctuations in Ca(Co<sub>1−x</sub>Ni<sub>x</sub>)<sub>2−y</sub>As<sub>2</sub> single crystals

ORAL

Abstract

The highly-frustrated itinerant magnetic system CaCo2-yAs2 exhibits A-type antiferromagnetic (AFM) order below TN = 52 K. From the magnetization M versus temperature T, magnetic field H, and heat capacity Cp(T, H) measurements it is found that TN decreases to 22 K with only 3% Ni substitution and is completely suppressed for x > 0.16. Magnetic susceptibility χ measurements reveal that strong ferromagnetic (FM) fluctuations develop for 0.11≤ x ≤ 0.52. The FM fluctuations for x = 0.21 and 0.31 are quasi-1D in nature, where χc >> χab. The Cp(T) measurements further reveal that the FM spin fluctuations are quantum in nature, where a logarithmic T-dependent upturn in Cp(T )/T is observed at low T and H = 0, that is suppressed with increasing H. A reentrant spin-glass behavior arising out of competing AFM and FM interactions is also observed for x = 0.11 and 0.16 below TN. No signature of any magnetic order or spin fluctuations is observed for x > 0.52 at T ≥ 1.8 K. Density functional theory (DFT) calculations show that the transition to nonmagnetic state occurs via a Stoner transition.

*This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-07CH11358.

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Publication: S. Pakhira et al. Phys. Rev. B 104, 094420 (2021).

Presenters

  • Santanu Pakhira

    • Ames Laboratory, USA

Authors

  • Santanu Pakhira

    • Ames Laboratory, USA

  • Yongbin Lee

    • Ames Laboratory, USA

  • Liqin Ke

    • Ames Laboratory, USA
    • Ames Laboratory, US DOE

  • V. Smetana

    • Stockholm University
    • Department of Materials and Environmental Chemistry, Stockholm University, Sweden
    • Stockholm University, Svante Arrhenius väg 16 C, 106 91 Stockholm, Sweden

  • Anja-verena Mudring

    • Stockholm University
    • Department of Materials and Environmental Chemistry, Stockholm University, Sweden

  • Tom W Heitmann

    • University of Missouri
    • The Missouri Research Reactor and Department of Physics and Astronomy, University of Missouri, USA
    • University of Missouri Research Reactor, University of Missouri, Columbia MO USA

  • David Vaknin

    • Ames Laboratory, USA
    • Iowa State University

  • D.C. Johnston

    • Ames Laboratory, USA
    • Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA