The innovation engine for new materials

Soren Bear

Soren Bear




University of California, Santa Barbara


Ganesh Pokharel

Faculty Sponsor(s): 

Stephen Wilson

Faculty Sponsor's Department(s): 


Project Title: 

Effect of Lu-doping on magnetic ordering in the quantum spin liquid candidate NaYbSe2

Project Description: 

Materials thought to host a quantum spin liquid (QSL) state exhibit an absence of long-range magnetic order even at very low temperatures. The ways in which this ground state can be manipulated are of interest to materials scientists and condensed matter physicists, with potential applications in data storage, quantum computing, and high-temperature superconductivity. We investigated the effect of Lu-doping on the ordering temperature of the quantum spin liquid candidate NaYbSe2. Lu-doping should dilute the competing interactions responsible for the QSL state and induce magnetic order at higher temperatures. Powder samples of NaYb1-xLuxSe2 (x = 0, 0.05, 0.10, 0.25) were synthesized using ball milling and solid state reaction techniques. The samples were characterized through powder X-ray diffraction (PXRD), magnetization measurements, and heat capacity measurements. The refinement of PXRD data indicates a perfect hexagonal crystal structure with symmetry R-3m. The unit cell volume decreases with the increase in Lu-doping. Magnetization measurements show no magnetic transition down to 1.8 K in all compositions. The fitting of a low temperature region of linear inverse magnetic susceptibility to the Curie-Weiss law reveals short-range antiferromagnetic correlations below ~15 K. The large ratios of the Curie-Weiss temperatures to the magnetic ordering temperatures indicate that the systems are highly frustrated. Heat capacity measurements reveal a broad upturn around 7 K that shifts weakly towards lower temperatures with doping. The electronic contribution to the heat capacity decreases with doping. These measurements show that Lu-doping does not have much effect on raising the ordering temperature within our measurement limit, indicating a quantum disordered ground state in NaYb1-xLuxSe2 (x = 0, 0.05, 0.10, 0.25).