Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb2Ti2O7

Time-of-flight neutron spectroscopy has been used to determine the crystalline electric field (CEF) Hamiltonian, eigenvalues and eigenvectors appropriate to the J=7/2 Yb3+ ion in the candidate quantum spin ice pyrochlore magnet Yb2Ti2O7. The precise ground state (GS) of this exotic, geometrically frustrated magnet is known to be sensitive to weak disorder associated with the growth of single crystals from the melt. Such materials display weak …