Real-space investigation of short-range magnetic correlations in fluoride pyrochlores NaCaCo2F7 and NaSrCo2F7 with magnetic pair distribution function analysis

作     者：Benjamin A. Frandsen Kate A. Ross Jason W. Krizan Gøran J. Nilsen Andrew R. Wildes Robert J. Cava Robert J. Birgeneau Simon J. L. Billinge 

作者机构：Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Department of Physics University of California Berkeley California 94720 USA Department of Physics Colorado State University Fort Collins Colorado 80523 USA Quantum Materials Program Canadian Institute for Advanced Research Toronto Ontario M5G 1Z8 Canada Department of Physics Princeton University Princeton New Jersey 08544 USA Institut Laue-Langevin CS 20156 38042 Grenoble Cédex 9 France ISIS Neutron and Muon Facility Rutherford Appleton Laboratory Didcot OX11 0QX United Kingdom Department of Materials Science and Engineering University of California Berkeley California 94720 USA Condensed Matter Physics and Materials Science Department Brookhaven National Laboratory Upton New York 11973 USA Department of Applied Physics and Applied Mathematics Columbia University New York New York 10027 USA 

出 版 物：《Physical Review Materials》 (Physic. Rev. Mat.)

年 卷 期：2017年第1卷第7期

页      面：074412-074412页

核心收录：

基　　金：Office of Basic Energy Science Office of Basic Energy Sciences Scientific User Facilities Division U.S. DOE U.S. DOE Office of Basic Energy Sciences U.S. Department of Energy, USDOE, (DE-AC02-05-CH11231, KC2202) U.S. Department of Energy, USDOE Office of Science, SC Oak Ridge National Laboratory, ORNL Division of Materials Sciences and Engineering, DMSE 

主　　题：Frustrated magnetism Neutron pair-distribution function analysis Neutron scattering 

摘      要：We present time-of-flight neutron total scattering and polarized neutron scattering measurements of the magnetically frustrated compounds NaCaCo2F7 and NaSrCo2F7, which belong to a class of recently discovered pyrochlore compounds based on transition metals and fluorine. The magnetic pair distribution function (mPDF) technique is used to analyze and model the total scattering data in real space. We find that a previously proposed model of short-range XY-like correlations with a length scale of 10–15 Å, combined with nearest-neighbor collinear antiferromagnetic correlations, accurately describes the mPDF data at low temperature, confirming the magnetic ground state in these materials. This model is further verified by the polarized neutron scattering data. From an analysis of the temperature dependence of the mPDF and polarized neutron scattering data, we find that short-range correlations persist on the nearest-neighbor length scale up to 200 K, approximately two orders of magnitude higher than the spin freezing temperatures of these compounds. These results highlight the opportunity presented by these new pyrochlore compounds to study the effects of geometric frustration at relatively high temperatures, while also advancing the mPDF technique and providing an opportunity to investigate a genuinely short-range-ordered magnetic ground state directly in real space.