Experimental evidence of a collinear antiferromagnetic ordering in the frustrated CoAl2O4 spinel

TitleExperimental evidence of a collinear antiferromagnetic ordering in the frustrated CoAl2O4 spinel
Publication TypeJournal Article
Year of Publication2013
AuthorsRoy B, Pandey A, Zhang Q, Heitmann TW, Vaknin D, Johnston DC, Furukawa Y
Journal TitlePhysical Review B
Volume88
Pages174415
Date Published11
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000327150400005
Keywordsglasses, liquid, magnetic-structure, metals, nmr, relaxation, RESONANCE, site
Abstract

Nuclear magnetic resonance (NMR), neutron diffraction (ND), x-ray diffraction, magnetic susceptibility., and specific-heat measurements on the frustrated A-site spinel CoAl2O4 compound reveal a collinear antiferromagnetic ordering belowTN = 9.8(2) K. Ahigh-quality powder sample characterized by x-ray diffraction that indicates a relatively low Co-Al inversion parameter x = 0.057(20) in (Co1-x Al x)[ Al2-x Co x] O-4, shows a broad maximum around 15 K in.(T) and a sharp peak at TN in heat capacity Cp. The average-ordered magnetic moment of Co2+ (S = 3/2) ions at the A site is estimated to be 2.4(1) mu B from NMR and 1.9(5) mu B from ND which are smaller than the expected value of 3 B for S = 3/2 and g = 2. Antiferromagnetic spin fluctuations and correlations in the paramagnetic state are revealed from the., NMR, and ND measurements, which are due to spin frustration and site inversion effects in the system. The ND data also show short-range dynamic magnetic ordering that persists to a temperature that is almost twice T-N.

URL<Go to ISI>://WOS:000327150400005
DOI10.1103/PhysRevB.88.174415