Spin glass transitions in the absence of chemical disorder for the pyrochlores A{sub 2}Sb{sub 2}O{sub 7} (A=Mn, Co, Ni)

Journal Article · Thu Apr 15 00:00:00 EDT 2010 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2010.01.025· OSTI ID:21372568

Zhou, H D ^[1]; Janik, J A ^[1]; Vogt, B ^[2]; Harter, A; Dalal, N S ^[3]; Gardner, J S ^[4]

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1. Department of Physics, Florida State University, Tallahassee, FL 32306-3016 (United States)
2. National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306-4005 (United States)
3. Department of Chemistry, Florida State University, Tallahassee, FL 32306-4390 (United States)
4. Indiana University, 2401 Milo B. Sampson Lane, Bloomington, IN 47408 (United States)

The pyrochlores in the series A{sub 2}Sb{sub 2}O{sub 7} have been synthesized and characterized as exhibiting spin glass transitions at T{sub SG}=41, 4.5, and 2.6 K (for A=Mn{sup 2+}S=5/2 , Co{sup 2+}S=3/2 and Ni{sup 2+}S=1, respectively) despite the lack of chemical disorder. Since the Curie-Weiss temperature remains essentially constant for all members in the series ({theta}{approx}-40K), the frustration index for these materials increases significantly as the moment size is reduced from f=|theta|/T{sub SG}=1.1 (Mn{sup 2+}), to 9.3 (Co{sup 2+}) to 14.6 (Ni{sup 2+}). There is also a corresponding change in the spin dynamics measured by the shift in the AC susceptibility signal as a function of frequency. These new materials provide an avenue to investigate the effect of quantum fluctuations on the Heisenberg pyrochlore lattice in the low spin limit, and show there is a dramatic change in the spin dynamics as the quantum regime is approached. - A comparison of the spin glass ordering temperature, T{sub SG}, and the frustration index f as a function of the spin for the pyrochlore series A{sub 2}Sb{sub 2}O{sub 7}. In the limit of low spin, the frustration index increases by an order of magnitude.

• OSTI ID: 21372568
• Journal Information: Journal of Solid State Chemistry, Vol. 183, Issue 4; Other Information: DOI: 10.1016/j.jssc.2010.01.025; PII: S0022-4596(10)00039-3; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COBALT COMPOUNDS
COBALT IONS
MAGNETIC PROPERTIES
MANGANESE COMPOUNDS
MANGANESE IONS
NICKEL COMPOUNDS
NICKEL IONS
OXIDES
PYROCHLORE
SPIN GLASS STATE
TEMPERATURE RANGE 0013-0065 K
CHALCOGENIDES
CHARGED PARTICLES
IONS
MINERALS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS