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Snyder J, Ueland BG, Slusky JS, Karunadasa H, Cava RJ, Mizel A, Schiffer P. Quantum-classical reentrant relaxation crossover in Dy2Ti2O7 spin ice. Phys Rev Lett 2003; 91:107201. [PMID: 14525500 DOI: 10.1103/physrevlett.91.107201] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2003] [Indexed: 05/24/2023]
Abstract
We have studied spin relaxation in the spin ice compound Dy2Ti2O7 through measurements of the ac magnetic susceptibility. While the characteristic spin-relaxation time (tau) is thermally activated at high temperatures, it becomes almost temperature independent below T(cross) approximately 13 K. This behavior, combined with nonmonotonic magnetic field dependence of tau, indicates that quantum tunneling dominates the relaxational process below that temperature. As the low-entropy spin ice state develops below T(ice) approximately 4 K, tau increases sharply with decreasing temperature, suggesting the emergence of a collective degree of freedom for which thermal relaxation processes again become important as the spins become strongly correlated.
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Affiliation(s)
- J Snyder
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Karunadasa H, Huang Q, Ueland BG, Schiffer P, Cava RJ. Ba2LnSbO6 and Sr2LnSbO6 (Ln = Dy, Ho, Gd) double perovskites: lanthanides in the geometrically frustrating fcc lattice. Proc Natl Acad Sci U S A 2003; 100:8097-102. [PMID: 12824460 PMCID: PMC166188 DOI: 10.1073/pnas.0832394100] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Magnetic ground states in solids often arise as a result of a delicate balance between competing factors. One currently active area of research in magnetic materials involves compounds in which long-range magnetic ordering at low temperatures is frustrated by the geometry of the crystalline lattice, a situation known as geometrical magnetic frustration. The number of systems known to display the effects of such frustration is growing, but those that are sufficiently simple from theoretical, chemical, and physical perspectives to allow for detailed understanding remain very few. A search for model compounds in this family has led us to the double perovskites Ba2LnSbO6 and Sr2LnSbO6 (Ln = Dy, Ho, and Gd) reported here. Ba2DySbO6,Ba2HoSbO6,Sr2DySbO6, and Sr2HoSbO6 are structurally characterized by powder neutron diffraction at ambient temperature. The trivalent lanthanides and pentavalent antimony are found to be fully ordered in the double-perovskite arrangement of alternating octahedra sharing corner oxygens. In such a structure, the lanthanide sublattice displays a classical fcc arrangement, an edge-shared network of tetrahedra known to result in geometric magnetic frustration. No magnetic ordering is observed in any of these compounds down to temperatures of 2 K, and in the case of the Dy-based compounds in particular, frustration of the magnetic ordering is clearly present. Lanthanide-based double perovskites are proposed to be excellent model systems for the detailed study of geometric magnetic frustration.
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Affiliation(s)
- H. Karunadasa
- Department of Chemistry, Princeton University,
Princeton, NJ 08544; Center for Neutron
Research, National Institute of Standards and Technology, Gaithersburg, MD
20899; Department of Physics and Materials
Research Institute, Pennsylvania State University, University Park, PA 16802;
and Princeton Materials Institute, Princeton
University, Princeton, NJ 08540
| | - Q. Huang
- Department of Chemistry, Princeton University,
Princeton, NJ 08544; Center for Neutron
Research, National Institute of Standards and Technology, Gaithersburg, MD
20899; Department of Physics and Materials
Research Institute, Pennsylvania State University, University Park, PA 16802;
and Princeton Materials Institute, Princeton
University, Princeton, NJ 08540
| | - B. G. Ueland
- Department of Chemistry, Princeton University,
Princeton, NJ 08544; Center for Neutron
Research, National Institute of Standards and Technology, Gaithersburg, MD
20899; Department of Physics and Materials
Research Institute, Pennsylvania State University, University Park, PA 16802;
and Princeton Materials Institute, Princeton
University, Princeton, NJ 08540
| | - P. Schiffer
- Department of Chemistry, Princeton University,
Princeton, NJ 08544; Center for Neutron
Research, National Institute of Standards and Technology, Gaithersburg, MD
20899; Department of Physics and Materials
Research Institute, Pennsylvania State University, University Park, PA 16802;
and Princeton Materials Institute, Princeton
University, Princeton, NJ 08540
| | - R. J. Cava
- Department of Chemistry, Princeton University,
Princeton, NJ 08544; Center for Neutron
Research, National Institute of Standards and Technology, Gaithersburg, MD
20899; Department of Physics and Materials
Research Institute, Pennsylvania State University, University Park, PA 16802;
and Princeton Materials Institute, Princeton
University, Princeton, NJ 08540
- To whom correspondence should be addressed. E-mail:
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