Bos, J.-W. G.

de Vries, M. A.

McLaughlin, Abbie

Physical Review B

English

The Ba2-xSrxYMoO6 double perovskites with a geometrically frustrated face centered Mo5+ (s= 1/2) sublattice have been investigated using neutron powder-diffraction, magnetic- susceptibility, and heat-capacity measurements. Reduction in the average A -site radius results in the distortion of the crystal structure from cubic for x=0 to monoclinic for x=2 without affecting the Y/Mo inversion (&lt;1%). Magnetic-susceptibility measurements evidence two paramagnetic regimes for all samples. The high-temperature (HT) Curie constants are independent of composition x [0.26 (1) emu mol-1 K-1] while the low-temperature (LT) value gradually increases from 0.04 (1) emu mol -1 K-1 for x=0 to -0.10 (1) emu mol-1 K -1. The HT Weiss temperature (?) increases from -159K (x=0) to -50K (x=2) while the LT values are -2.3 (3) K for x&lt;2 and +10K for x=2. Neutron powder diffraction does not evidence any Neel ordering. The x=2 sample is weakly ferromagnetic below 8 K (Msat ~0.1 µB /Mo in 1 T at 5 K) which is consistent with the small positive LT Weiss temperature. The magnetic data are consistent with a valence bond glass state where the bulk of the spins condense into spin singlets as previously observed for Ba2 YMoO6, leaving a small fraction of the spins isolated or only weak ferromagnetically coupled to each other. © 2010 The American Physical Society.</p

McLaughlin, A. C.

De Vries, M. A.

Bos, J. W G

Heriot Watt Pure

Persistence of the valence bond glass state in the double perovskites Ba2-xSrxYMoO6

The Ba2−xSrxYMoO6 double perovskites with a geometrically frustrated face centered Mo5+ s = 1/2 sublattice have been investigated using neutron powder-diffraction, magnetic-susceptibility, and heat-capacity measure-ments. Reduction in the average A-site radius results in the distortion of the crystal structure from cubic for x = 0 to monoclinic for x = 2 without affecting the Y/Mo inversion (&lt;1%). Magnetic-susceptibility measurements evidence two paramagnetic regimes for all samples. The high-temperature (HT) Curie constants are independent of composition x [0.26(1) emu mol−1 K−1] while the low-temperature (LT) value gradually increases from 0.04͑1͒ emu mol−1 K−1 for x = 0 to −0.10(1) emu mol−1 K−1. The HT Weiss temperature increases from −159 K (x = 0) to −50 K (x = 2) while the LT values are −2.3(3) K for x &lt;2 and +10 K for x = 2. Neutron powder diffraction does not evidence any Neel ordering. The x = 2 sample is weakly ferromagnetic below 8 K (M sat ~ 0.1 muB / Mo in 1 T at 5 K) which is consistent with the small positive LT Weiss temperature. The magnetic data are consistent with a valence bond glass state where the bulk of the spinscondense into spin singlets as previously observed for Ba2YMoO6, leaving a small fraction of the spins isolated or only weak ferromagnetically coupled to each other.<br/

de Vries, Mark A.

Bos, J-W G.

Edinburgh Research Explorer

Persistence of the valence bond glass state in the double perovskites Ba2−xSrxYMoO6

Mclaughlin, AC

de Vries, MA

Bos, JWG

University of St. Andrews - Pure

Persistence of the valence bond glass state in the double perovskites Ba2-xSrxYMoO6

Aberdeen University Research

https://doi.org/10.1103/PhysRevB.82.094424

Persistence of the valence bond glass state in the double perovskites Ba2-xSrxYMoO6

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Heriot Watt Pure

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Heriot Watt Pure