Quantum critical behavior of the hyperkagome magnet
β-Mn-type family alloys Mn3 TX (T = Co, Rh, and Ir; X = Si and Ge) have a three-dimensional antiferromagnetic (AF) corner-shared triangular network, i.e., the hyperkagome lattice. The antiferromagnet Mn3 RhSi shows magnetic short-range order over a wide temperature range of approximately 500 K above the Néel temperature TN of 190 K. In this family of compounds, as the lattice parameter decreases, the long-range magnetic ordering temperature decreases. Mn3 CoSi has the smallest lattice parameter and the lowest TN in the family. The quantum critical point (QCP) from AF to the quantum paramagnetic state is expected near a cubic lattice parameter of 6.15 Å. Although the Néel temperature of Mn3 CoSi is only 140 K, the emergence of the quantum critical behavior in Mn3 CoSi is discussed. We study how the magnetic short-range order appears in Mn3 CoSi by using neutron scattering, μ SR, and bulk characterization such as specific heat capacity. According to the results, the neutron scattering intensity of the magnetic short-range order in Mn3 CoSi does not change much at low temperatures from that of Mn3 RhSi , although the μ SR short-range order temperature of Mn3 CoSi is largely suppressed to 240 K from that of Mn3 RhSi . Correspondingly, the volume fraction of the magnetic short-range order regions, as shown by the initial asymmetry drop ratio of μ SR above TN, also becomes small. Instead, the electronic-specific heat coefficient γ of Mn3 CoSi is the largest in this Mn3T Si system, possibly due to the low-energy spin fluctuation near the quantum critical point.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 2284038
- Alternate ID(s):
- OSTI ID: 2301663
- Journal Information:
- Physical Review Research, Journal Name: Physical Review Research Vol. 6 Journal Issue: 1; ISSN 2643-1564
- Publisher:
- American Physical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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