Signatures of Novel Spin Liquids in Kagome-Like Lattices

Par Rico Pohle, OIST, Japan

Mardi 04 Juillet, 14h, Salle des séminaires (215), 2ème étage, Bâtiment A4N

Abstract :

Frustrated Magnets provide a playground for many-body phenomena, where competing magnetic short-range interactions allow for novel magnetic ground states. They offer the possibility to explore unconventional types of order, and to achieve spin liquids, which defy conventional thermodynamic ordering mechanisms down to the lowest temperatures. While conventional magnetic order can easily be seen in the magnetic susceptibility and spin-spin correlation functions, absence of order is very hard to characterise [1].

In this talk I will explain, based on two frustrated models with kagome-like structure made of triangular units, what kind of exotic thermodynamic and dynamical signatures appear in classical spin liquids.
First, I will consider the eponymous “shuriken” lattice. By using complementary analytical and numerical techniques, namely Husimi–tree calculations and Monte Carlo simulations, one can show that spin liquids perform a Curie-law crossover between different correlated regimes [2], providing a powerful signature which explains the difficulty for a precise estimate of the Curie-Weiss temperature in experiments[3].
Then, I will focus on recent neutron scattering experiments of Ca10Cr7O28 [4], where ring-like features suggest a new kind of spiral spin liquid, characterised by coexisting ordered spiral grounds states, allowing for a highly degenerate ground state manifold [5].

[1] Leon Balents, Nature 464, 11 (2010)
[2] Pohle et al. PRB 94, 014429 (2016)
[3] Nag et al. Journal of Magnetism and Magnetic Materials 424, 93–98 (2017)
[4] Balz et al. Nature Physics 12, 942–949 (2016)
[5] Fouet et al. Eur. Phys. J. B 20, 241–254 (2001)