Spin liquid state

Keywords Charge transfer solid Electronic dimensionality Functional organic solid Ionicity diagram Organic metal Organic superconductor Phase transition Quantum spin liquid state Switching... 

Spin Disordered State (Quantum Spin Liquid State) Neighboring Superconductivity. .. 103... 

Emergence of Superconducting State Next to Spin Liquid State. 105... 

New Spin State Originated from Strong Spin Frustrations Quantum Spin Liquid State... 

Figure 17c,d compares the line shapes of NMR absorption of k-(ET)2 Cu2(CN)3 and k-(ET)2Cu[N(CN)2]C1, respectively. K-(ET)2Cu[N(CN)2]a exhibited a drastic change below 27 K owing to the formation of three-dimensional AF ordering, while, the absorption band of k-(ET)2Cu2(CN)3 remained almost invariant down to 32 mK, indicating a nonspin-ordered state the quantum spin liquid state [342, 349-357]. 

Controversial discussions ensued concerning the magiutude of the gap of the spin liquid state. Specific heat measurements suggested a gapless nature [358], while thermal conductivity measurements suggested a small gap [359]. Furthermore, there is an abnormality in lattice near 5-6 K which was detected by NMR [357] and thermal expansion [360] measurements, indicating that the lattice is not frozen even at 5-6 K. 

Following ic-(ET)2Cu2(CN)3, five materials [364], including EtMe3Sb[Pd (dmit)2]2 as an organic solid [365], have been found to have quantum spin liquid states however, superconductivity has been confirmed only for k-(ET)2Cu2(CN)3. 

Shimizu Y, Kurosaki Y, Miyagawa K, Kanoda K, Maesato M, Saito G (2005) NMR study of the spin-liquid state and Mott transition in the spin-frustrated organic system, k-(ET)2Cu2(CN)3. Synth Met 152 393-396... 

Ohira S, Shimizu Y, Kanoda K, Saito G (2006) Spin liquid state in k-(BEDT-TTF)2Cu2(CN)3 studied by muon spin relaxation method. J Low Temp Phys 142 153-158... 

Yamashita S, Nakazawa Y, Oguni M, Oshima Y, Nojiri H, Shimizu Y, Miyagawa K, Kanoda K (2008) Thermodynamic properties of a spin-1/2 spin-liquid state in a /c-type organic salt Nat Phys 4 459 62... 

Yamashita M, Nakata N, Kasahara Y, Sasaki T, Yoneyama N, Kobayashi N, Fujimoto S, Shibauchi T, Matsuda Y (2009) Thermal-transport measurements in a quantum spin-liquid state of the frustrated triangular magnet k-(BEDT-TTF)2Cu2(CN)3. Nat Phys 5 44-47... 

Itou T, Oyamada A, Maegawa S, Tamura M, Kato R (2007) Spin-liquid state in an organic spin-1/2 system on a triangular lattice, EtMe3Sb[Pd(dmit)2]2- J Phys Condens Matter 19 145247/1-5... 

Summary YbPdSb is magnetically unstable. The [xSR data on a sample that does not develop long-range AFM order show that the material enters a spin-liquid state instead. This state is characterized by dynamic short-range correlations whose fluctuation rate becomes temperature independent below 0.3 K at the comparatively low value of 60 MHz. Probably one deals with quantum fluctuations that are interpreted here as local moment fluctuations induced by the dynamics of fluctuating bonds of Kondo spin pairs. 

Figure 2.8 A representation of the RVB spin liquid state on a TP lattice. The ground state is a superposition of states in which each spin is AF coupled to another to form 5 = 0 dimers...

RVB picture, is that overall, a spin singlet ground state will result. As well, another characteristic is the presence of significant spin dynamics down to the lowest temperatures. There are relatively few accepted examples of the spin liquid state, the pyrochlore oxide Tb2Ti20y being one. ... 

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