On a lattice composed of triangular plaquettes where antiferromagnetic exchange interactions between localized spins cannot be simultaneously satisfied, the system becomes geometrically frustrated with magnetically disordered phases remarkably different from a simple paramagnet. Spin liquid belongs to one of these exotic states, in which a macroscopic degeneracy of the ground state gives rise to the rich spectrum of collective phenomena. Here, we report on the discovery of a new magnetic state in the heterostructures derived from a single unit cell (111)-oriented spinel CoCr2O4 sandwiched between nonmagnetic Al2O3 spacers. The artificial quasi-two-dimensional material composed of three triangle and one kagome atomic planes shows a degree of magnetic frustration which is almost two orders of magnitude enlarged compared to the bulk crystals. Combined resonant X-ray absorption and torque magnetometry measurements confirm that the designer system exhibits no sign of spin ordering down to 30 mK, implying a possible realization of a quantum spin liquid state in the two dimensional limit.
@article{arxiv.1911.00100,
title = {Quantum spin liquids by geometric lattice design},
author = {Xiaoran Liu and T. Asaba and Qinghua Zhang and Yanwei Cao and B. Pal and S. Middey and P. S. Anil Kumar and M. Kareev and Lin Gu and D. D. Sarma and P. Shafer and E. Arenholz and J. W. Freeland and Lu Li and J. Chakhalian},
journal= {arXiv preprint arXiv:1911.00100},
year = {2019}
}