Suppression of antiferromagnetic order and strong ferromagnetic spin fluctuations in Ni-doped CaCo2As2 single crystals
| Autor: | Pakhira, Santanu, Lee, Y., Ke, Liqin, Smetana, V., Mudring, A. -V., Heitmann, Thomas, Vaknin, David, Johnston, D. C. |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 104, 094420 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.104.094420 |
| Popis: | CaCo2As2 is a unique itinerant system having strong magnetic frustration. Here we report the effect of electron doping on the physical properties resulting from Ni substitutions for Co. The A-type antiferromagnetic transition temperature TN = 52 K for x = 0 decreases to 22 K with only 3 percent Ni substitution and is completely suppressed for x > 0.11. For 0.11 < x < 0.52 strong ferromagnetic (FM) fluctuations develop as revealed by magnetic susceptibility chi(T) measurements. Heat-capacity Cp(T) measurements reveal the presence of FM quantum spin fluctuations for 0.11 < x < 0.52. Our density-functional theory (DFT) calculations confirm that FM fluctuations are enhanced by Ni substitutions for Co. The Sommerfeld electronic heat-capacity coefficient is enhanced for x = 0, 0.21, and 0.42 by about a factor of two compared to DFT calculations of the bare density of states at the Fermi energy. The crystals with x > 0.52 do not exhibit FM spin fluctuations or magnetic order, which was found from the DFT calculations to arise from a Stoner transition. Neutron-diffraction studies of crystals with x = 0.11 and 0.16 found no evidence of A-type ordering as observed in CaCo2As2 or of other common magnetic structures. Comment: 19 pages, 18 captioned figures, 7 tables, 79 references |
| Databáze: | arXiv |
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