A search for disorder in the spin glass double perovskites Sr2CaReO6 and Sr2MgReO6 using neutron diffraction and neutron pair distribution function analysis

作者：Greedan J E^*; Derakhshan Shahab; Ramezanipour F; Siewenie J; Proffen Th

来源：Journal of Physics: Condensed Matter , 2011, 23(16): 164213.

DOI：10.1088/0953-8984/23/16/164213

The geometrically frustrated, B-site ordered, S = 1/2, double perovskites Sr2CaReO6 and Sr2MgReO6, which show spin frozen magnetic ground states, have been investigated using neutron powder diffraction (ND) and neutron pair distribution NPDF) analysis in a search for evidence for atomic positional disorder. For both materials, data were taken above and below the spin freezing temperatures of similar to 14 K and similar to 45 K for the CaRe and MgRe phases, respectively. In both cases the fully B-site ordered model was in excellent agreement with the data, both ND and NPDF, at all temperatures studied. Thus, the structure of these materials, from the average and the local perspectives, is very well described by the fully B-site ordered model, which raises questions concerning the origin of the spin glass ground state. These results are compared with those for the spin glass pyrochlore Y2Mo2O7 and other B-site ordered double perovskites.

• 出版日期2011-4-27