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arXiv · 1910.09963

Disordered quantum spin state in the stripe lattice system consisting of triangular and square tilings

Y. Saito·H. Nakamura·M. Sawada·T. Yamazaki·S. Fukuoka·N. Matsunaga·K. Nomura·M. Dressel·A. Kawamoto
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Abstract

Quantum fluctuations originating phase competition or geometrical frustration of spins lead to novel states such as a quantum critical point and a quantum spin liquid where the strong quantum fluctuations suppress any ordered states even at 0 K. Utilizing site-selective NMR for a quasi-two dimensional organic conductor $\lambda$-(STF)$_2$GaCl$_4$, we investigate the non-magnetic insulating phase of the stripe lattice system consisting of triangular and square tilings. We found development of AF spin fluctuations with decreasing temperature. Regardless of large enhancement of spin-lattice relaxation rate $1/T_1$ owing to critical slowing down below 10 K, no long-range magnetic ordering was observed down to 1.63 K two orders of magnitude less than the exchange interaction $J/k_{\rm B} \simeq$ 194 K. Moreover, $1/T_1$ saturated below 3.5 K. These results are in stark contrast to observed behaviors so far in other non-magnetic ground states discussed in terms of spin liquids, demonstrating realization of an exotic quantum state accompanying quantum criticality.

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Y. Saito, H. Nakamura, M. Sawada, T. Yamazaki, S. Fukuoka, N. Matsunaga, K. Nomura, M. Dressel, A. Kawamoto. 2019-10-22. Disordered quantum spin state in the stripe lattice system consisting of triangular and square tilings. https://arxiv.org/abs/1910.09963

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