Magnetic Stress-Driven Metal-Insulator Transition in Strongly Correlated Antiferromagnetic CrN

Traditionally, the Coulomb repulsion or Peierls instability causes the metal-insulator phase transitions in strongly correlated quantum materials. In comparison, magnetic stress is predicted to drive the metal insulator transition in materials exhibiting strong spin-lattice coupling. However, this mechanism lacks experimental validation and an in-depth understanding. Here we demonstrate the existence of the magnetic stress-driven metal-insulator transition in an archetypal material, chromium nitride. Structural, magnetic, electronic transport characterization, and first-principles modeling analysis show that the phase transition temperature in CrN is directly proportional to the strain-controlled anisotropic magnetic stress. The compressive strain increases the magnetic stress, leading to the much-coveted room-temperature transition. In contrast, tensile strain and the inclusion of nonmagnetic cations weaken the magnetic stress and reduce the transition temperature. This discovery of a new physical origin of metal-insulator phase transition that unifies spin, charge, and lattice degrees of freedom in correlated materials marks a new paradigm and could lead to novel device functionalities.

Automated summary

In this study, we demonstrated the existence of a magnetic stress-driven metal-insulator transition in Chromium Nitride. Through structural, magnetic, and electronic transport characterization, as well as first-principles modeling analysis, we found that the phase transition temperature in CrN is directly proportional to the strain-controlled anisotropic magnetic stress. Compressive strain increases the magnetic stress, leading to a room-temperature transition. In contrast, tensile strain and the inclusion of nonmagnetic cations weaken the magnetic stress and reduce the transition temperature. This discovery unifies spin, charge, and lattice degrees of freedom in correlated materials and holds potential for novel device functionalities.