p-f hybridization in the ferromagnetic semiconductor HoN

The electronic structure of thin film HoN has been studied using soft x-ray spectroscopy. The combination of soft x-ray emission, x-ray absorption, and photoemission techniques yields direct evidence for hybridization between the N 2p and the Ho 4f states, previously unseen in this or related rare earth nitride systems. The N 2p states extend up to 10 eV below the Fermi level to nearly twice the binding energy as previously believed. Optical spectroscopy yields a minimum direct gap of 1.48 eV. In light of these results, we identify HoN as a prime candidate for spin-diffusion and spintronics applications.