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Abstract:
We report on the crystal structure, physical properties, and electronic
structure calculations for the ternary pnictide compound EuCr2As2. X-ray
diffraction studies confirmed that EuCr2As2 crystalizes in the
ThCr2Si2-type tetragonal structure (space group I4/mmm). The Eu ions are
in a stable divalent state in this compound. Eu moments in EuCr2As2
order magnetically below T-m = 21 K. A sharp increase in the magnetic
susceptibility below Tm and the positive value of the paramagnetic Curie
temperature obtained from the Curie-Weiss fit suggest dominant
ferromagnetic interactions. The heat capacity exhibits a sharp.-shape
anomaly at Tm, confirming the bulk nature of the magnetic transition.
The extracted magnetic entropy at the magnetic transition temperature is
consistent with the theoretical value R ln(2S + 1) for S = 7/2 of the
Eu2+ ion. The temperature dependence of the electrical resistivity.(T)
shows metallic behavior along with an anomaly at 21 K. In addition, we
observe a reasonably large negative magnetoresistance (similar to -24%)
at lower temperature. Electronic structure calculations for EuCr2As2
reveal a moderately high density of states of Cr-3d orbitals at the
Fermi energy, indicating that the nonmagnetic state of Cr is unstable
against magnetic order. Our density functional calculations for EuCr2As2
predict a G-type AFM order in the Cr sublattice. The electronic
structure calculations suggest a weak interlayer coupling of the Eu
moments.
