Pressure-induced collapsed-tetragonal phase in SrCo2As2

Journal Article · Tue Dec 08 04:00:00 EST 2015 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.92.224103· OSTI ID:1247715

Jayasekara, W. T.; Kaluarachchi, U. S.; Ueland, B.; Pandey, Abhishek; Lee, Y. B.; Taufour, V.; Sapkota, A.; Kothapalli, K.; Sangeetha, N. S.; Feng, Yejun

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 = 5.9GPa, on SrCo2As2. 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.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division; USDOE Office of Science - Office of Basic Energy Sciences - Scientific User Facilities Division
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1247715
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 22 Vol. 92; ISSN 1098-0121
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English