Gapless Quantum Spin Liquid in an Organic Spin-1/2 Triangular-Latticeκ−H3(Cat-EDT-TTF)2

Abstract

We report the results of SQUID and torque magnetometry of an organic spin-1/2 triangular-lattice κ-H(3)(Cat-EDT-TTF)(2). Despite antiferromagnetic exchange coupling at 80-100 K, we observed no sign of antiferromagnetic order down to 50 mK owing to spin frustration on the triangular lattice. In addition, we found nearly temperature-independent susceptibility below 3 K associated with Pauli paramagnetism. These observations suggest the development of gapless quantum spin liquid as the ground state. On the basis of a comparative discussion, we point out that the gapless quantum spin liquid states in organic systems share a possible mechanism, namely the formation of a band with a Fermi surface possibly attributed to spinons.

Absence of Magnetic Long Range Order in Ba3ZnRu2O9: A Spin-Liquid Candidate in the S = 3/2 Dimer Lattice

“…Organic candidates consist of ill-defined localized magnetic moments where the magnetic exchange interaction is comparable to the charge gap. [5][6][7] On the other hand, inorganic candidates suffer from unwanted disorder/impurity/nonstoichiometry. Na 4 Ir 3 O 8 8 shows a spin-glass-like transition near 6-7 K, 9,10 whereas ZnCu 3 (OH) 6 Cl 2 11 and Ba 3 CuSb 2 O 9 12 include a considerable intermixture of cations.…”

Temperature Dependence of Crystal Structures and Band Parameters in Quantum Spin Liquid β′-EtMe3Sb[Pd(dmit)2]2 and Related Materials

“…Such geometrical frustration becomes stronger near the regular triangular lattice, namely t /t = 1. The QSL state is realized in some molecular conductors with a slightly distorted triangular lattice [13,14,17,18] including the EtMe 3 Sb salt. The reason why the QSL is observed in the distorted triangular lattice system in molecular conductors remains an open question.…”

Development of Novel Functional Organic Crystals by Utilizing Proton- and π-Electron-Donating/Accepting Abilities

“…79 A new type of dynamic phenomena, electronic properties, and functionalities was discovered by successfully combining the π-electron donating ability of the TTF system with the proton donating/accepting and Hbonding abilities of the catechol moiety. Further materials development 25,27 and also collaboration with researchers from other fields, such as solid state physics and quantum chemistry, 18,19,21,24,28 are indispensable for the progress of this new fascinating area of functional organic crystals, where H-bonds play a key role in the electronic structure and physical properties in cooperation with π-electrons.…”

“…On the other hand, H-ST remains paramagnetic down to 2 K without a phase transition, showing quantum spin liquid-like behavior, 8 as seen in H-TTF. 18 Interestingly, as shown in Figure 7, (1) 22 The latter (2) might be simply due to the difference in the oxidation potentials of the parent donor molecules, H 2 Cat-EDT-ST (+0.48 V) and H 2 Cat-EDT-TTF (+0.40 V).…”

“…In each charge-rich dimer, a spin-singlet pair should be formed, which results in the nonmagnetic band-insulating ground state seen in the physical property measurements (Figure 4). Considering the fact that such physical property changes do not occur in the isostructural H-TTF even at very low temperatures (T = 50 mK), 18,19 it can be concluded that the phase transition and property switching phenomena in D-TTF are caused not by the conventional Coulomb interactions of π electrons but by the deuterium displacement or H-bond dynamics. This means that the H-bond dynamics changes the intermolecular π electron interactions, and thus, the H-bonds and π electrons are strongly coupled in this system.…”