Emergence of orbital two-channel Kondo effect in epitaxial TiN thin films

The continual scaledown and stringent defect control in electronic devices are opening up frontiers in Kondo effect-a powerful testbed for probing magnetic impurity coupling to a continuum of electronic states. In disordered ferromagnets, degenerate quantum states like two-level systems (TLS) with a pseudo-half spin can couple with the continuum to mimic Kondo physics, creating the orbital two-channel Kondo (2CK) effect below the characteristic Kondo temperature (T-K). By employing vacuum-annealing to inject similar to 12 at.% nitrogen vacancies (V-N) in TiN1-x films, we generated room-temperature ferromagnetic ordering with 13.6 emu g(-1) saturation magnetization. The transport characteristics exhibited non-Fermi-liquid (NFL) behavior below T-K of 20.2 K. The orbital 2CK effect is signified by a clear transition from logarithmic (T < T-0 similar to 4(0) K), to square-root dependence (T < T-K) and subsequent deviation from it (T < T-D similar to 10 K) in resistivity upturn behavior in three distinct low-temperature regimes. By controlling V-N, we establish the necessity of ferromagnetism and ultrafast tunneling centers for generating orbital 2CK effect and NFL behavior in disordered metallic systems, extending their scope in non-magnetic nanomaterials.

Automated summary

This study demonstrates room-temperature ferromagnetic ordering in TiN1-x films by injecting nitrogen vacancies, with non-Fermi liquid behavior observed below 20.2K. The resistivity shows a transition from logarithmic to square-root dependence at low temperatures, indicating the existence of the orbital two-channel Kondo effect.