### Session Q8: Focus Session: Spin Liquids II

11:15 AM–2:15 PM, Wednesday, February 29, 2012
Room: 208

Chair: Arthur Ramirez, UC Santa Cruz

Abstract ID: BAPS.2012.MAR.Q8.1

### Abstract: Q8.00001 : Absence of magnetic order and unusual spin dynamics in the spin liquid candidate Na$_4$Ir$_3$O$_8$

11:15 AM–11:27 AM

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#### Authors:

Peter Baker
(ISIS Facilty, STFC Rutherford Appleton Laboratory)

Francis Pratt
(ISIS Facilty, STFC Rutherford Appleton Laboratory)

Dharmalingham Prabhakaran
(Oxford University Department of Physics)

Andrew Steele
(Oxford University Department of Physics)

Tom Lancaster
(Oxford University Department of Physics)

Bill Hayes
(Oxford University Department of Physics)

Stephen Blundell
(Oxford University Department of Physics)

Na$_4$Ir$_3$O$_8$ has spin-1/2 iridium ions on a hyperkagome lattice of corner sharing triangles and is a candidate three-dimensional spin liquid [1], which has led to active theoretical study [2,3,4]. Previously reported measurements have shown no evidence for magnetic ordering down to temperatures around three orders of magnitude below the Curie-Weiss constant of $\sim 650$K [1]. We have carried out muon-spin relaxation measurements which exclude magnetic ordering above 55mK. The field dependence of the muon spin relaxation rate provides further information on the spin dynamics with a temperature-dependent crossover between power laws at intermediate fields suggesting that more than one energy scale is relevant to the fluctuations in this system. $[1]$ Y.\ Okamoto {\em et al.}, Phys.\ Rev.\ Lett. {\bf 99}, 137207 (2007). $[2]$ M.\ J.\ Lawler {\em et al.}, Phys.\ Rev.\ Lett. {\bf 100}, 227201 (2008). $[3]$ Yi Zhou {\em et al.}, Phys.\ Rev.\ Lett. {\bf 101}, 197201 (2008). $[4]$ E.\ J.\ Bergholtz {\em et al.}, Phys.\ Rev.\ Lett. {\bf 105}, 237202 (2010).

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2012.MAR.Q8.1