Search for a quantum spin liquid in the Kitaev honeycomb lattice, alpha-RuCl3

• Applicant: Dr. Seung-Ho Baek, Ph.D.
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 391462523

The key objective of this proposal is to search for a Kitaev quantum spin liquid (QSL) and relevant novel quasiparticle excitations emerging from spin fractionalization by means of nuclear magnetic resonance (NMR). For this purpose, we take alpha-RuCl3 as a model system for the realization of a Kitaev QSL. Since the ground state of alpha-RuCl3 is in the proximity of a QSL, it should be highly sensitive to the strengths and the signs of the couplings in the Kitaev Hamiltonian. Thus one can fine-tune the ground state of alpha-RuCl3 by manipulating the coupling parameters in the Hamiltonian in a variety of avenues:(1) Application of very high magnetic fields(2) Magnetic site dilution with nonmagnetic ions, e.g. Ir3+ (S=0)(3) Substituting Ru with paramagnetic impurities, e.g. Cr3+ (S=3/2)(4) Application of chemical pressure by substituting Cl with other halide elements with larger radius (Br and I) (5) Intercalating alkali elements (Na or K) between the layers to incorporate charge carriers to induce novel metallic phases.Each of these avenues has its own merit and potential, and thus will provide a different piece of information that are useful for the ultimate understanding of Kitaev physics.

• DFG Programme: Research Grants