Measurement of the Mott insulating gap in Ca3Ru2O7 by tunneling spectroscopy
Abstract
The bilayered Ca3Ru2O7 adopts an orthorhombic structure with the tilting and rotation of RuO6 octahdera in the basal plane. It is thus highly anisotropic magnetically and electronically. The extensive d-electron orbitals generate strong coupling between spin-orbit and lattice, resulting in an exotic ground state and lead to interesting properties at low temperatures. For instance, it undergoes a transition from a paramagnetic metallic state to an antiferromagnetic metallic state as the temperature is lowered to 56K, and subsequently another transition, a Mott transition, at a lower temperature of 48K. We have prepared Ca3Ru2O7/Al2O3/Ag tunnel junctions to measure the density of states of Ca3Ru2O7 at low temperatures. The Mott insulating gap is determined to be ∼0.07eV when it first opens up at 48K, but the gap continues to grow with decreasing temperature. In some junctions, the density of states displays unusual activities in the temperature range of the antiferromagnetic metallic state, between 48K and 56K. Results of this study, in particular the temperature dependence of the gap structure in the density of states will be presented and discussed.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2007
- Bibcode:
- 2007APS..MARS13011B