Orbital Angular Momentum-Driven Ferromagnetism with Magnetic Anisotropy and Electronic Structure of Epitaxial Neodymium Nitride

Neodymium-based permanent magnets are fundamental to modern technologies, underpinning high-performance applications in electronics, renewable energy, and advanced medical systems. Among emerging neodymium compounds, neodymium nitride (NdN) has attracted significant attention due to its unique electronic structure, where strongly localized 4<i>f</i> orbitals and strong spin-orbit coupling are anticipated to drive exceptional magnetic behavior. Here, we show conclusive experimental evidence of orbital angular momentum-driven ferromagnetic ordering and prominent magnetic anisotropy in epitaxial, near-stoichiometric NdN thin films synthesized using ultrahigh vacuum deposition techniques. Magnetization and X-ray magnetic circular dichroism measurements reveal a dominant 4<i>f</i> orbital moment of 5.14 μ_<i>B</i>, contributing to a total magnetic moment of 2.43 μ_<i>B</i> per formula unit at 4 K, close to the first-principles density functional theory calculated values. Complementary synchrotron-radiation photoelectron spectroscopy, along with the theoretical calculations, uncovers occupied 4<i>f</i> states ∼6.4 eV below the Fermi level, contributing to the orbital-driven ferromagnetism in NdN. Moreover, the high crystalline quality of the NdN films is further supported by the structural characterization and vibrational properties. The intrinsic orbital angular momentum-driven magnetism of NdN positions it as a promising platform for next-generation orbitronic devices beyond conventional spintronics.