TY - JOUR
T1 - Frustrated fcc antiferromagnet Ba2YOsO6
T2 - Structural characterization, magnetic properties, and neutron scattering studies
AU - Kermarrec, E.
AU - Marjerrison, C. A.
AU - Thompson, C. M.
AU - Maharaj, D. D.
AU - Levin, K.
AU - Kroeker, S.
AU - Granroth, G. E.
AU - Flacau, R.
AU - Yamani, Z.
AU - Greedan, J. E.
AU - Gaulin, B. D.
N1 - Publisher Copyright:
© 2015 American Physical Society.
PY - 2015/2/26
Y1 - 2015/2/26
N2 - We report the crystal structure, magnetization, and neutron scattering measurements on the double perovskite Ba2YOsO6. The Fm3¯m space group is found both at 290 K and 3.5 K with cell constants a0=8.3541(4) Å and 8.3435(4) Å, respectively. Os5+ (5d3) ions occupy a nondistorted, geometrically frustrated face-centered-cubic (fcc) lattice. A Curie-Weiss temperature θ∼-700 K suggests the presence of a large antiferromagnetic interaction and a high degree of magnetic frustration. A magnetic transition to long-range antiferromagnetic order, consistent with a type-I fcc state below TN∼69 K, is revealed by magnetization, Fisher heat capacity, and elastic neutron scattering, with an ordered moment of 1.65(6) μB on Os5+. The ordered moment is much reduced from either the expected spin-only value of ∼3 μB or the value appropriate to 4d3 Ru5+ in isostructural Ba2YRuO6 of 2.2(1) μB, suggesting a role for spin-orbit coupling (SOC). Triple-axis neutron scattering measurements of the order parameter suggest an additional first-order transition at T=67.45 K, and the existence of a second-ordered state. Time-of-flight inelastic neutron results reveal a large spin gap Δ∼17 meV, unexpected for an orbitally quenched, d3 electronic configuration. We discuss this in the context of the ∼5 meV spin gap observed in the related Ru5+,4d3 cubic double perovskite Ba2YRuO6, and attribute the ∼3 times larger gap to stronger SOC present in this heavier, 5d, osmate system.
AB - We report the crystal structure, magnetization, and neutron scattering measurements on the double perovskite Ba2YOsO6. The Fm3¯m space group is found both at 290 K and 3.5 K with cell constants a0=8.3541(4) Å and 8.3435(4) Å, respectively. Os5+ (5d3) ions occupy a nondistorted, geometrically frustrated face-centered-cubic (fcc) lattice. A Curie-Weiss temperature θ∼-700 K suggests the presence of a large antiferromagnetic interaction and a high degree of magnetic frustration. A magnetic transition to long-range antiferromagnetic order, consistent with a type-I fcc state below TN∼69 K, is revealed by magnetization, Fisher heat capacity, and elastic neutron scattering, with an ordered moment of 1.65(6) μB on Os5+. The ordered moment is much reduced from either the expected spin-only value of ∼3 μB or the value appropriate to 4d3 Ru5+ in isostructural Ba2YRuO6 of 2.2(1) μB, suggesting a role for spin-orbit coupling (SOC). Triple-axis neutron scattering measurements of the order parameter suggest an additional first-order transition at T=67.45 K, and the existence of a second-ordered state. Time-of-flight inelastic neutron results reveal a large spin gap Δ∼17 meV, unexpected for an orbitally quenched, d3 electronic configuration. We discuss this in the context of the ∼5 meV spin gap observed in the related Ru5+,4d3 cubic double perovskite Ba2YRuO6, and attribute the ∼3 times larger gap to stronger SOC present in this heavier, 5d, osmate system.
UR - https://www.scopus.com/pages/publications/84923899657
U2 - 10.1103/PhysRevB.91.075133
DO - 10.1103/PhysRevB.91.075133
M3 - Article
AN - SCOPUS:84923899657
SN - 1098-0121
VL - 91
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 7
M1 - 075133
ER -