LiYbSe: Frustrated Magnetism in the Pyrochlore Lattice.

Three-dimensionally (3D) frustrated magnets generally exist in the magnetic diamond and pyrochlore lattices, in which quantum fluctuations suppress magnetic orders and generate highly entangled ground states. LiYbSe in a previously unreported pyrochlore lattice was discovered from LiCl flux growth. Distinct from the quantum spin liquid (QSL) candidate NaYbSe hosting a perfect triangular lattice of Yb, LiYbSe crystallizes in the cubic pyrochlore structure with space group F3 (No. 227). The Yb ions in LiYbSe are arranged on a network of corner-sharing tetrahedra, which is particularly susceptible to geometrical frustration. According to our temperature-dependent magnetic susceptibility measurements, the dominant antiferromagnetic interaction in LiYbSe is expected to appear around 8 K. However, no long-range magnetic order is detected in thermomagnetic measurements above 70 mK. Specific heat measurements also show magnetic correlations shifting with applied magnetic field with a degree of missing entropy that may be related to the slight mixture of Yb on the Li site. Such magnetic frustration of Yb is rare in pyrochlore structures. Thus, LiYbSe shows promise in intrinsically realizing disordered quantum states like QSL in pyrochlore structures.