### 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.Q8.5

### Abstract: Q8.00005 : Field-Dependent Instability of the Candidate Quantum Spin Liquid in EtMe$_3$Sb[Pd(dmit)$_2$]$_2$ as Revealed by NMR

12:03 PM–12:15 PM

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#### Authors:

Georgios Koutroulakis
(Los Alamos National Laboratory)

Tong Zhou
(UCLA)

Stuart E. Brown
(UCLA)

Joe D. Thompson
(Los Alamos National Laboratory)

Reizo Kato
(RIKEN)

In recent years, the two-dimensional spin-$1/2$ triangular lattice of the organic salt EtMe$_3$Sb[Pd(dmit)$_2$]$_2$ has emerged as a candidate for the realization of a quantum spin liquid. Furthermore, thermal conductivity and nuclear magnetic resonance (NMR) experiments unveiled the presence of a low-temperature instability in the spin liquid state, the opening of a spin gap. We performed a detailed $^{13}$C NMR study on this material at low temperatures \mbox{($30$mK$\leq T\leq 1.5$ K)} and for a wide range of external magnetic field values \mbox{($B_0=0.6-9$T)}. In finite fields, a clear break in the temperature derivative of the spin-lattice relaxation is observed at a temperature $T_m(B_0)$, with $T_m$ following the empirical form $T_m(B_0)\sim \left| B_0-B_c\right| ^{1/2}$. Moreover, a uniform broadening of the NMR line for finite fields suggests the presence of a small field-induced staggered magnetization. We discuss these results in the context of possible instabilities, and existing thermodynamic data.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2012.MAR.Q8.5