Anomalously field-susceptible spin clusters emerging in the electric-dipole liquid candidate κ-(ET) 2 Hg(SCN) 2 Br

• Published in: Science advances 2022-12, Vol.8 (51), p.eabn1680
• Main Authors: Urai, Mizuki, Miyagawa, Kazuya, Watanabe, Yuta, Zhilyaeva, Elena I, Torunova, Svetlana A, Lyubovskaya, Rimma N, Drichko, Natalia, Kanoda, Kazushi
• Format: Article
• Language: English
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.abn1680

Mutual interactions in many-body systems bring about various exotic phases, among which liquid-like states failing to order due to frustration are of keen interest. The organic system with an anisotropic triangular lattice of molecular dimers, κ-(ET) Hg(SCN) Br, has been suggested to host a dipole liquid arising from intradimer charge-imbalance instability, possibly offering an unprecedented stage for the spin degrees of freedom. Here, we show that an extraordinary unordered/unfrozen spin state having soft matter-like spatiotemporal characteristics emerges in this system. H nuclear magnetic resonance (NMR) spectra and magnetization measurements indicate that gigantic, staggered moments are nonlinearly and inhomogeneously induced by a magnetic field, whereas the moments vanish in the zero-field limit. The analysis of the NMR relaxation rate signifies that the moments fluctuate at a characteristic frequency slowing down to below megahertz at low temperatures. The inhomogeneity, local correlation, and slow dynamics indicative of middle-scale dynamical correlation length of several nanometers suggest novel frustration-driven spin clusterization.