Evolution of orbital excitations from insulating to superconducting MgTi2O4 films

DOI: 10.1103/PhysRevB.107.L121108

Authors: Qizhi Li (Peking Universtiy) , Abhishek Nag (Diamond Light Source) , Xiquan Zheng (Peking University) , Fucong Chen (Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences) , Jie Yuan (Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences) , Kui Jin (Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences) , Yi Lu (Nanjing University) , Ke-Jin Zhou (Diamond Light Source) , Yingying Peng (Peking University; Collaborative Innovation Center of Quantum Matter (China))
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 107

State: Published (Approved)
Published: March 2023

Abstract: Spinel oxides are well-known functional materials but rarely show superconductivity. Recently, emergent superconductivity was discovered in MgTi 2 O 4 , which is attributed to the increase of electron doping and the suppression of orbital order. Here, we utilized Ti L -edge resonant inelastic x-ray scattering to study the orbital excitations in superconducting (SC) and insulating MgTi 2 O 4 films. We find that the spectral weight of orbital excitations is enhanced and the energy of t 2 g intraband excitation is softened in the SC film compared to the insulating one, suggesting higher electron doping and a suppressed orbital order gap in the SC sample. These observations were further supported by our multiplet calculations using the minimal two-site model. Our results provide spectroscopic evidence for the competition between orbital order and superconductivity in MgTi 2 O 4 and shed light on searching for novel superconductors in spinel oxides.

Journal Keywords: Quasiparticles & collective excitations; Superconductor-insulator transition; Low-temperature superconductors; Spinels; Exact diagonalization; Many-body techniques; Resonant inelastic x-ray scattering

Subject Areas: Materials, Physics


Instruments: I21-Resonant Inelastic X-ray Scattering (RIXS)

Added On: 28/03/2023 17:51

Discipline Tags:

Superconductors Quantum Materials Physics Materials Science

Technical Tags:

Scattering Spectroscopy Resonant Inelastic X-ray Scattering (RIXS) X-ray Absorption Spectroscopy (XAS)