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Renormalized behavior and proximity of BaCo 2 As 2 to a magnetic quantum critical point

2009; American Physical Society; Volume: 79; Issue: 2 Linguagem: Inglês

10.1103/physrevb.79.024512

1550-235X

Athena S. Sefat, David J. Singh, Rongying Jin, Michael A. McGuire, B. C. Sales, David Mandrus,

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We report synthesis and single-crystal measurements of magnetic, transport, and thermal properties of single crystalline ${\text{BaCo}}_{2}{\text{As}}_{2}$ as well as first-principles calculations of the electronic structure and magnetic behavior. These results show that ${\text{BaCo}}_{2}{\text{As}}_{2}$ is a highly renormalized paramagnet in proximity to a quantum critical point, presumably of ferromagnetic character and that ${\text{BaFeNiAs}}_{2}$ behaves similarly. These results are discussed in relation to the properties of $\text{Ba}{(\text{Fe},\text{Co})}_{2}{\text{As}}_{2}$ and $\text{Ba}{(\text{Fe},\text{Ni})}_{2}{\text{As}}_{2}$, which are superconducting for low Co and Ni concentrations.