Pressure-induced collapsed-tetragonal phase in SrCo2As2

We present high-energy x-ray diffraction data under applied pressures up to p = 29 GPa, neutron diffraction measurements up to p = 1.1GPa, and electrical resistance measurements up to p = 5.9 GPa, on SrCo2As2. Here, our x-ray diffraction data demonstrate that there is a first-order transition betwee...

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Veröffentlicht in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2015-12, Vol.92 (22)
Hauptverfasser: Jayasekara, W. T., Kaluarachchi, U. S., Ueland, B. G., Pandey, Abhishek, Lee, Y. B., Taufour, V., Sapkota, A., Kothapalli, K., Sangeetha, N. S., Fabbris, G., Veiga, L. S. I., Feng, Yejun, dos Santos, A. M., Bud'ko, S. L., Harmon, B. N., Canfield, P. C., Johnston, D. C., Kreyssig, A., Goldman, A. I.
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Sprache:eng
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Zusammenfassung:We present high-energy x-ray diffraction data under applied pressures up to p = 29 GPa, neutron diffraction measurements up to p = 1.1GPa, and electrical resistance measurements up to p = 5.9 GPa, on SrCo2As2. Here, our x-ray diffraction data demonstrate that there is a first-order transition between the tetragonal (T) and collapsed-tetragonal (cT) phases, with an onset above approximately 6 GPa at T = 7K. The pressure for the onset of the cT phase and the range of coexistence between the T and cT phases appears to be nearly temperature independent. The compressibility along the a axis is the same for the T and cT phases, whereas, along the c axis, the cT phase is significantly stiffer, which may be due to the formation of an As-As bond in the cT phase. Our resistivity measurements found no evidence of superconductivity in SrCo2As2 for p ≤ 5.9 GPa and T ≥ 1.8 K. The resistivity data also show signatures consistent with a pressure-induced phase transition for p ≳ 5.5 GPa. Single-crystal neutron diffraction measurements performed up to 1.1 GPa in the T phase found no evidence of stripe-type or A-type antiferromagnetic ordering down to 10 K. Spin-polarized total-energy calculations demonstrate that the cT phase is the stable phase at high pressure with a c/a ratio of 2.54. Furthermore, these calculations indicate that the cT phase of SrCo2As2 should manifest either A-type antiferromagnetic or ferromagnetic order.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.92.224103