Kovacevic, I.Babkevich, P.Jeong, M.Piatek, J. O.Boero, G.Rønnow, Henrik M.2017-02-172017-02-172017-02-17201610.1103/PhysRevB.94.214433https://infoscience.epfl.ch/handle/20.500.14299/134584WOS:000391005100002We present direct local-probe evidence for strongly hybridized nuclear-electronic spin states of an Ising ferromagnet LiHoF4 in a transverse magnetic field. The nuclear-electronic states are addressed via a magnetic resonance in the GHz frequency range using coplanar resonators and a vector network analyzer. The magnetic resonance spectrum is successfully traced over the entire field-temperature phase diagram, which is remarkably well reproduced by mean-field calculations. Our method can be directly applied to a broad class of materials containing rare-earth ions for probing the substantially mixed nature of the nuclear and electronic moments.MPBHtext::journal::journal article::research article